size overflow in ipv6_get_l4proto/br_dev_xmit, followed by memleak attempt

Discuss usability issues, general maintenance, and general support issues for a grsecurity-enabled system.

Moderators: spender, PaX Team

size overflow in ipv6_get_l4proto/br_dev_xmit, followed by memleak attempt

Postby StalkR » Wed Sep 14, 2016 5:59 am

Hello,

I noticed an issue on an old 4.5.2 (grsecurity-3.1-4.5.2-201604290633.patch) with an uptime of ~40 days (config).
Unfortunately I don't know what triggered it, so I don't know how to reproduce.
I'll run a 4.7.3 (grsecurity-3.1-4.7.3-201609072139.patch) and update if it reproduces, in the meantime here are the details if anyone wants to take a look.

Log is interesting, 3 detected size overflow (I use pax_size_overflow_report_only) followed by a detected kernel memory leak attempt:
Code: Select all
PAX: size overflow detected in function ipv6_get_l4proto net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c:83
PAX: size overflow detected in function __dev_queue_xmit include/linux/skbuff.h
PAX: size overflow detected in function br_dev_xmit include/linux/skbuff.h:2147
PAX: kernel memory leak attempt detected from ffff880104d5f2c0 (radix_tree_node) (1294 bytes)


Full log:
Code: Select all
Sep 14 05:00:56 kernel: [3306540.486709] PAX: size overflow detected in function ipv6_get_l4proto net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c:83 cicus.107_26 max, count: 1, decl: ipv6_skip_exthdr$
Sep 14 05:00:56 kernel: [3306540.489457] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.5.2-grsec #1
Sep 14 05:00:56 kernel: [3306540.489458] Hardware name: System manufacturer System Product Name/P8H77-I, BIOS 1001 02/01/2013
Sep 14 05:00:56 kernel: [3306540.489459]  ffffffff81e048c7 0000000000000286 0000000000000000 ffff88041fb83ac8
Sep 14 05:00:56 kernel: [3306540.489461]  ffffffff813e35ab 0000000000000001 ffffffffa043f478 0000000000000053
Sep 14 05:00:56 kernel: [3306540.489463]  ffff88041fb83af8 ffffffff8122b206 00000000ffffffd0 ffff88040c11f500
Sep 14 05:00:56 kernel: [3306540.489465] Call Trace:
Sep 14 05:00:56 kernel: [3306540.489466]  <IRQ>  [<ffffffff813e35ab>] dump_stack+0x4e/0x7b
Sep 14 05:00:56 kernel: [3306540.489475]  [<ffffffffa043f478>] ? invmap+0x62/0xa75 [nf_conntrack_ipv6]
Sep 14 05:00:56 kernel: [3306540.489478]  [<ffffffff8122b206>] report_size_overflow+0x6e/0x90
Sep 14 05:00:56 kernel: [3306540.489480]  [<ffffffffa043e1d7>] ipv6_get_l4proto+0xaf/0xc0 [nf_conntrack_ipv6]
Sep 14 05:00:56 kernel: [3306540.489486]  [<ffffffffa041af97>] nf_conntrack_in+0x9f/0x490 [nf_conntrack]
Sep 14 05:00:56 kernel: [3306540.489488]  [<ffffffffa04378bd>] ? nf_ct_frag6_gather+0x4b5/0x11f0 [nf_defrag_ipv6]
Sep 14 05:00:56 kernel: [3306540.489491]  [<ffffffffa043e4b8>] ipv6_conntrack_in+0x20/0x40 [nf_conntrack_ipv6]
Sep 14 05:00:56 kernel: [3306540.489493]  [<ffffffff81756199>] nf_iterate+0x81/0xa0
Sep 14 05:00:56 kernel: [3306540.489495]  [<ffffffff81756218>] nf_hook_slow+0x60/0xb0
Sep 14 05:00:56 kernel: [3306540.489498]  [<ffffffff817e4ccf>] ipv6_rcv+0x4a7/0x6d0
Sep 14 05:00:56 kernel: [3306540.489500]  [<ffffffff81828905>] ? tpacket_rcv+0x5d/0xb00
Sep 14 05:00:56 kernel: [3306540.489502]  [<ffffffff811b7947>] ? __alloc_pages_nodemask+0x15f/0xb40
Sep 14 05:00:56 kernel: [3306540.489503]  [<ffffffff817e42b8>] ? ip6_make_skb+0x1e0/0x1e0
Sep 14 05:00:56 kernel: [3306540.489506]  [<ffffffff81711cc9>] __netif_receive_skb_core+0x381/0xce0
Sep 14 05:00:56 kernel: [3306540.489508]  [<ffffffff8181f100>] ? ipv6_gro_receive+0x368/0xb90
Sep 14 05:00:56 kernel: [3306540.489510]  [<ffffffff81712641>] __netif_receive_skb+0x19/0x80
Sep 14 05:00:56 kernel: [3306540.489512]  [<ffffffff817126c6>] netif_receive_skb_internal+0x1e/0x90
Sep 14 05:00:56 kernel: [3306540.489513]  [<ffffffff81713ba1>] napi_gro_receive+0x79/0xd0
Sep 14 05:00:56 kernel: [3306540.489517]  [<ffffffffa00dc815>] rtl8169_poll+0x2fd/0x760 [r8169]
Sep 14 05:00:56 kernel: [3306540.489519]  [<ffffffff81712f99>] net_rx_action+0x341/0x510
Sep 14 05:00:56 kernel: [3306540.489522]  [<ffffffff810df5ae>] __do_softirq+0x106/0x210
Sep 14 05:00:56 kernel: [3306540.489524]  [<ffffffff810df808>] irq_exit+0x80/0x90
Sep 14 05:00:56 kernel: [3306540.489526]  [<ffffffff81058949>] do_IRQ+0x51/0x100
Sep 14 05:00:56 kernel: [3306540.489529]  [<ffffffff8184e40b>] common_interrupt+0x8b/0x8b
Sep 14 05:00:56 kernel: [3306540.489530]  <EOI>  [<ffffffff816bb212>] ? cpuidle_enter_state+0x10a/0x1f0
Sep 14 05:00:56 kernel: [3306540.489534]  [<ffffffff816bb207>] ? cpuidle_enter_state+0xff/0x1f0
Sep 14 05:00:56 kernel: [3306540.489535]  [<ffffffff816bb368>] cpuidle_enter+0x20/0x40
Sep 14 05:00:56 kernel: [3306540.489537]  [<ffffffff8111f0d6>] call_cpuidle+0x3e/0x70
Sep 14 05:00:56 kernel: [3306540.489539]  [<ffffffff8111f3ed>] cpu_startup_entry+0x175/0x230
Sep 14 05:00:56 kernel: [3306540.489541]  [<ffffffff81092149>] start_secondary+0x1d1/0x290
Sep 14 05:00:56 kernel: [3306540.489548] PAX: size overflow detected in function __dev_queue_xmit include/linux/skbuff.h:2147 cicus.2247_338 max, count: 237, decl: mac_header; num: 0; context: sk_bu$
Sep 14 05:00:56 kernel: [3306540.492277] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.5.2-grsec #1
Sep 14 05:00:56 kernel: [3306540.492278] Hardware name: System manufacturer System Product Name/P8H77-I, BIOS 1001 02/01/2013
Sep 14 05:00:56 kernel: [3306540.492279]  ffffffff81e048c7 0000000000000286 0000000000000000 ffff88041fb83970
Sep 14 05:00:56 kernel: [3306540.492280]  ffffffff813e35ab 0000000000000001 ffffffff81bd82f8 0000000000000863
Sep 14 05:00:56 kernel: [3306540.492282]  ffff88041fb839a0 ffffffff8122b206 ffff88040b2d2020 0000000100000040
Sep 14 05:00:56 kernel: [3306540.492283] Call Trace:
Sep 14 05:00:56 kernel: [3306540.492284]  <IRQ>  [<ffffffff813e35ab>] dump_stack+0x4e/0x7b
Sep 14 05:00:56 kernel: [3306540.492288]  [<ffffffff8122b206>] report_size_overflow+0x6e/0x90
Sep 14 05:00:56 kernel: [3306540.492289]  [<ffffffff8171656d>] __dev_queue_xmit+0x555/0x6c0
Sep 14 05:00:56 kernel: [3306540.492290]  [<ffffffff817166ea>] dev_queue_xmit+0x12/0x30
Sep 14 05:00:56 kernel: [3306540.492293]  [<ffffffff81721a4d>] neigh_resolve_output+0x135/0x200
Sep 14 05:00:56 kernel: [3306540.492294]  [<ffffffff817defec>] ip6_finish_output2+0x194/0x4a0
Sep 14 05:00:56 kernel: [3306540.492295]  [<ffffffff817de788>] ? ac6_proc_exit+0x30/0x30
Sep 14 05:00:56 kernel: [3306540.492297]  [<ffffffff81756199>] ? nf_iterate+0x81/0xa0
Sep 14 05:00:56 kernel: [3306540.492299]  [<ffffffff817e3652>] ip6_finish_output+0xaa/0x120
Sep 14 05:00:56 kernel: [3306540.492300]  [<ffffffff817e189e>] ip6_output+0x66/0x110
Sep 14 05:00:56 kernel: [3306540.492301]  [<ffffffff817e35a8>] ? ip6_fragment+0x1200/0x1200
Sep 14 05:00:56 kernel: [3306540.492303]  [<ffffffff817de8b5>] ip6_forward_finish+0x3d/0x60
Sep 14 05:00:56 kernel: [3306540.492304]  [<ffffffff817e1e38>] ip6_forward+0x4f0/0xa60
Sep 14 05:00:56 kernel: [3306540.492306]  [<ffffffff817f10be>] ? ip6_route_input_lookup.isra.53+0x46/0x60
Sep 14 05:00:56 kernel: [3306540.492308]  [<ffffffff817de878>] ? ndisc_hashfn+0x40/0x40
Sep 14 05:00:56 kernel: [3306540.492309]  [<ffffffff817e4308>] ip6_rcv_finish+0x50/0xe0
Sep 14 05:00:56 kernel: [3306540.492310]  [<ffffffff817e4b7f>] ipv6_rcv+0x357/0x6d0
Sep 14 05:00:56 kernel: [3306540.492312]  [<ffffffff81828905>] ? tpacket_rcv+0x5d/0xb00
Sep 14 05:00:56 kernel: [3306540.492313]  [<ffffffff811b7947>] ? __alloc_pages_nodemask+0x15f/0xb40
Sep 14 05:00:56 kernel: [3306540.492314]  [<ffffffff817e42b8>] ? ip6_make_skb+0x1e0/0x1e0
Sep 14 05:00:56 kernel: [3306540.492316]  [<ffffffff81711cc9>] __netif_receive_skb_core+0x381/0xce0
Sep 14 05:00:56 kernel: [3306540.492318]  [<ffffffff8181f100>] ? ipv6_gro_receive+0x368/0xb90
Sep 14 05:00:56 kernel: [3306540.492320]  [<ffffffff81712641>] __netif_receive_skb+0x19/0x80
Sep 14 05:00:56 kernel: [3306540.492322]  [<ffffffff817126c6>] netif_receive_skb_internal+0x1e/0x90
Sep 14 05:00:56 kernel: [3306540.492323]  [<ffffffff81713ba1>] napi_gro_receive+0x79/0xd0
Sep 14 05:00:56 kernel: [3306540.492326]  [<ffffffffa00dc815>] rtl8169_poll+0x2fd/0x760 [r8169]
Sep 14 05:00:56 kernel: [3306540.492327]  [<ffffffff81712f99>] net_rx_action+0x341/0x510
Sep 14 05:00:56 kernel: [3306540.492329]  [<ffffffff810df5ae>] __do_softirq+0x106/0x210
Sep 14 05:00:56 kernel: [3306540.492331]  [<ffffffff810df808>] irq_exit+0x80/0x90
Sep 14 05:00:56 kernel: [3306540.492333]  [<ffffffff81058949>] do_IRQ+0x51/0x100
Sep 14 05:00:56 kernel: [3306540.492334]  [<ffffffff8184e40b>] common_interrupt+0x8b/0x8b
Sep 14 05:00:56 kernel: [3306540.492335]  <EOI>  [<ffffffff816bb212>] ? cpuidle_enter_state+0x10a/0x1f0
Sep 14 05:00:56 kernel: [3306540.492338]  [<ffffffff816bb207>] ? cpuidle_enter_state+0xff/0x1f0
Sep 14 05:00:56 kernel: [3306540.492339]  [<ffffffff816bb368>] cpuidle_enter+0x20/0x40
Sep 14 05:00:56 kernel: [3306540.492340]  [<ffffffff8111f0d6>] call_cpuidle+0x3e/0x70
Sep 14 05:00:56 kernel: [3306540.492342]  [<ffffffff8111f3ed>] cpu_startup_entry+0x175/0x230
Sep 14 05:00:56 kernel: [3306540.492344]  [<ffffffff81092149>] start_secondary+0x1d1/0x290
Sep 14 05:00:56 kernel: [3306540.492346] PAX: size overflow detected in function br_dev_xmit include/linux/skbuff.h:2147 cicus.208_90 max, count: 1, decl: mac_header; num: 0; context: sk_buff;
Sep 14 05:00:56 kernel: [3306540.495071] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.5.2-grsec #1
Sep 14 05:00:56 kernel: [3306540.495072] Hardware name: System manufacturer System Product Name/P8H77-I, BIOS 1001 02/01/2013
Sep 14 05:00:56 kernel: [3306540.495073]  ffffffff81e048c7 0000000000000286 0000000000000000 ffff88041fb838b0
Sep 14 05:00:56 kernel: [3306540.495074]  ffffffff813e35ab 0000000000000001 ffffffffa0410fe4 0000000000000863
Sep 14 05:00:56 kernel: [3306540.495076]  ffff88041fb838e0 ffffffff8122b206 ffff88040c11f500 0000000100000040
Sep 14 05:00:56 kernel: [3306540.495077] Call Trace:
Sep 14 05:00:56 kernel: [3306540.495078]  <IRQ>  [<ffffffff813e35ab>] dump_stack+0x4e/0x7b
Sep 14 05:00:56 kernel: [3306540.495084]  [<ffffffffa0410fe4>] ? br_dst_default_metrics+0x3ba4/0x4318 [bridge]
Sep 14 05:00:56 kernel: [3306540.495086]  [<ffffffff8122b206>] report_size_overflow+0x6e/0x90
Sep 14 05:00:56 kernel: [3306540.495089]  [<ffffffffa03f94aa>] br_dev_xmit+0x202/0x2b0 [bridge]
Sep 14 05:00:56 kernel: [3306540.495090]  [<ffffffff81715c8c>] dev_hard_start_xmit+0x364/0x570
Sep 14 05:00:56 kernel: [3306540.495092]  [<ffffffff81715494>] ? validate_xmit_skb.isra.123.part.124+0x1c/0x4b0
Sep 14 05:00:56 kernel: [3306540.495093]  [<ffffffff8171660d>] __dev_queue_xmit+0x5f5/0x6c0
Sep 14 05:00:56 kernel: [3306540.495094]  [<ffffffff817166ea>] dev_queue_xmit+0x12/0x30
Sep 14 05:00:56 kernel: [3306540.495096]  [<ffffffff81721a4d>] neigh_resolve_output+0x135/0x200
Sep 14 05:00:56 kernel: [3306540.495098]  [<ffffffff817defec>] ip6_finish_output2+0x194/0x4a0
Sep 14 05:00:56 kernel: [3306540.495099]  [<ffffffff817de788>] ? ac6_proc_exit+0x30/0x30
Sep 14 05:00:56 kernel: [3306540.495100]  [<ffffffff81756199>] ? nf_iterate+0x81/0xa0
Sep 14 05:00:56 kernel: [3306540.495102]  [<ffffffff817e3652>] ip6_finish_output+0xaa/0x120
Sep 14 05:00:56 kernel: [3306540.495103]  [<ffffffff817e189e>] ip6_output+0x66/0x110
Sep 14 05:00:56 kernel: [3306540.495104]  [<ffffffff817e35a8>] ? ip6_fragment+0x1200/0x1200
Sep 14 05:00:56 kernel: [3306540.495106]  [<ffffffff817de8b5>] ip6_forward_finish+0x3d/0x60
Sep 14 05:00:56 kernel: [3306540.495107]  [<ffffffff817e1e38>] ip6_forward+0x4f0/0xa60
Sep 14 05:00:56 kernel: [3306540.495109]  [<ffffffff817f10be>] ? ip6_route_input_lookup.isra.53+0x46/0x60
Sep 14 05:00:56 kernel: [3306540.495110]  [<ffffffff817de878>] ? ndisc_hashfn+0x40/0x40
Sep 14 05:00:56 kernel: [3306540.495112]  [<ffffffff817e4308>] ip6_rcv_finish+0x50/0xe0
Sep 14 05:00:56 kernel: [3306540.495113]  [<ffffffff817e4b7f>] ipv6_rcv+0x357/0x6d0
Sep 14 05:00:56 kernel: [3306540.495114]  [<ffffffff81828905>] ? tpacket_rcv+0x5d/0xb00
Sep 14 05:00:56 kernel: [3306540.495116]  [<ffffffff811b7947>] ? __alloc_pages_nodemask+0x15f/0xb40
Sep 14 05:00:56 kernel: [3306540.495117]  [<ffffffff817e42b8>] ? ip6_make_skb+0x1e0/0x1e0
Sep 14 05:00:56 kernel: [3306540.495119]  [<ffffffff81711cc9>] __netif_receive_skb_core+0x381/0xce0
Sep 14 05:00:56 kernel: [3306540.495121]  [<ffffffff8181f100>] ? ipv6_gro_receive+0x368/0xb90
Sep 14 05:00:56 kernel: [3306540.495123]  [<ffffffff81712641>] __netif_receive_skb+0x19/0x80
Sep 14 05:00:56 kernel: [3306540.495124]  [<ffffffff817126c6>] netif_receive_skb_internal+0x1e/0x90
Sep 14 05:00:56 kernel: [3306540.495126]  [<ffffffff81713ba1>] napi_gro_receive+0x79/0xd0
Sep 14 05:00:56 kernel: [3306540.495128]  [<ffffffffa00dc815>] rtl8169_poll+0x2fd/0x760 [r8169]
Sep 14 05:00:56 kernel: [3306540.495130]  [<ffffffff81712f99>] net_rx_action+0x341/0x510
Sep 14 05:00:56 kernel: [3306540.495131]  [<ffffffff810df5ae>] __do_softirq+0x106/0x210
Sep 14 05:00:56 kernel: [3306540.495133]  [<ffffffff810df808>] irq_exit+0x80/0x90
Sep 14 05:00:56 kernel: [3306540.495135]  [<ffffffff81058949>] do_IRQ+0x51/0x100
Sep 14 05:00:56 kernel: [3306540.495136]  [<ffffffff8184e40b>] common_interrupt+0x8b/0x8b
Sep 14 05:00:56 kernel: [3306540.495137]  <EOI>  [<ffffffff816bb212>] ? cpuidle_enter_state+0x10a/0x1f0
Sep 14 05:00:56 kernel: [3306540.495140]  [<ffffffff816bb207>] ? cpuidle_enter_state+0xff/0x1f0
Sep 14 05:00:56 kernel: [3306540.495141]  [<ffffffff816bb368>] cpuidle_enter+0x20/0x40
Sep 14 05:00:56 kernel: [3306540.495143]  [<ffffffff8111f0d6>] call_cpuidle+0x3e/0x70
Sep 14 05:00:56 kernel: [3306540.495144]  [<ffffffff8111f3ed>] cpu_startup_entry+0x175/0x230
Sep 14 05:00:56 kernel: [3306540.495145]  [<ffffffff81092149>] start_secondary+0x1d1/0x290
Sep 14 05:00:56 kernel: [3306540.495189] PAX: From xxx: kernel memory leak attempt detected from ffff880104d5f2c0 (radix_tree_node) (1294 bytes)
Sep 14 05:00:56 kernel: [3306540.496583] CPU: 1 PID: 8219 Comm: qemu-system-x86 Not tainted 4.5.2-grsec #1
Sep 14 05:00:56 kernel: [3306540.496585] Hardware name: System manufacturer System Product Name/P8H77-I, BIOS 1001 02/01/2013
Sep 14 05:00:56 kernel: [3306540.496586]  ffffffff81e048c7 0000000000000286 0000000000000000 ffffc9000d20bb20
Sep 14 05:00:56 kernel: [3306540.496588]  ffffffff813e35ab ffff88041fa8d260 ffff880104d5f2c0 000000000000050e
Sep 14 05:00:56 kernel: [3306540.496590]  ffffc9000d20bb50 ffffffff8122b5e3 000000000000050e 0000000000000000
Sep 14 05:00:56 kernel: [3306540.496591] Call Trace:
Sep 14 05:00:56 kernel: [3306540.496594]  [<ffffffff813e35ab>] dump_stack+0x4e/0x7b
Sep 14 05:00:56 kernel: [3306540.496597]  [<ffffffff8122b5e3>] __check_object_size.part.50+0x10b/0x1f0
Sep 14 05:00:56 kernel: [3306540.496599]  [<ffffffff8122b6f6>] __check_object_size+0x2e/0x50
Sep 14 05:00:56 kernel: [3306540.496601]  [<ffffffff813fd99d>] copy_to_iter+0x1c5/0x820
Sep 14 05:00:56 kernel: [3306540.496603]  [<ffffffff813fda2b>] ? copy_to_iter+0x253/0x820
Sep 14 05:00:56 kernel: [3306540.496605]  [<ffffffff817028a2>] skb_copy_datagram_iter+0x5a/0x220
Sep 14 05:00:56 kernel: [3306540.496608]  [<ffffffff815c7808>] tun_do_read+0x350/0x790
Sep 14 05:00:56 kernel: [3306540.496609]  [<ffffffff815c7dc4>] tun_chr_read_iter+0x5c/0xb0
Sep 14 05:00:56 kernel: [3306540.496611]  [<ffffffff81221999>] __vfs_read+0xf1/0x120
Sep 14 05:00:56 kernel: [3306540.496612]  [<ffffffff81222c4f>] vfs_read+0xc7/0x250
Sep 14 05:00:56 kernel: [3306540.496614]  [<ffffffff812241dd>] sys_read+0x45/0xb0
Sep 14 05:00:56 kernel: [3306540.496616]  [<ffffffff8184d919>] entry_SYSCALL_64_fastpath+0x12/0x83
Sep 14 05:00:56 kernel: [3306540.496618]  [<ffffffff8184d949>] ? entry_SYSCALL_64_fastpath+0x42/0x83
Sep 14 05:00:56 kernel: [3306540.496622] grsec: banning user with uid 1004 until system restart for suspicious kernel crash


uid 1004 was running qemu-system-x86 with a Linux VM, traffic including IPv6, connected to the host via a tap device plugged into a bridge.

Code pointers:

Let me know if you want me to provide the -fdump-tree-all -fdump-ipa-all for these objects.
StalkR
 
Posts: 3
Joined: Wed May 15, 2013 7:23 pm

Re: size overflow in ipv6_get_l4proto/br_dev_xmit, followed by memleak attempt

Postby PaX Team » Thu Sep 15, 2016 9:04 am

this is quite a bunch of problems ;). i'd say that of the size overflow reports the first one is what matters, the others may just be cascading effects. this first one may be an upstream problem, you should ask them for clarification before we can do anything about it. what happens is that ipv6_skip_exthdr takes an int for its second parameter however an unsigned int is passed in when called from ipv6_get_l4proto. this uint comes from an uint parameter (nhoff) of ipv6_get_l4proto which is called indirectly by nf_conntrack_in which passes in the return value of skb_network_offset, an int itself to add even more int/uint conversions to the picture. the simplified code flow is something like this:
Code: Select all
ret = l3proto->get_l4proto(skb, skb_network_offset(skb),&dataoff, &protonum);
static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff, unsigned int *dataoff, u_int8_t *protonum)
unsigned int extoff = nhoff + sizeof(struct ipv6hdr);
protoff = ipv6_skip_exthdr(skb, extoff, &nexthdr, &frag_off);
int ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp,__be16 *frag_offp)
what can happen here is that skb_network_offset returns a negative number whose absolute value is larger than the size of ipv6hdr which the overflow plugin will catch since the resulting big positive value in extoff would be above INT_MAX. now whether this or something else happened i can't tell, you'd have to be able to reproduce this and print out the relevant variables to know for sure. it's at least clear that the ->get_l4proto callback doesn't expect negative nhoff values so some higher level invariant must have been violated here and at this point i'm out of my depth ;).

as for the kernel memory leak attempt, that may very well be a consequence of the previous problem and i think it's a real kernel bug since a radix_tree_node should never ever be copied to userland, so i guess we're dealing with a heap overflow (well, overread) or a use-after-free bug here.
PaX Team
 
Posts: 2310
Joined: Mon Mar 18, 2002 4:35 pm


Return to grsecurity support