This is a note to let you know that I've just added the patch titled
ipv6: fix potential NULL deref in fib6_add()
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipv6-fix-potential-null-deref-in-fib6_add.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 41cb79f7ddb5fe961eb4aa680b2c0d75c7b3cded
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Wed Nov 29 16:06:30 2023 +0000
ipv6: fix potential NULL deref in fib6_add()
[ Upstream commit 75475bb51e78a3f54ad2f69380f2a1c985e85f2d ]
If fib6_find_prefix() returns NULL, we should silently fallback
using fib6_null_entry regardless of RT6_DEBUG value.
syzbot reported:
WARNING: CPU: 0 PID: 5477 at net/ipv6/ip6_fib.c:1516 fib6_add+0x310d/0x3fa0 net/ipv6/ip6_fib.c:1516
Modules linked in:
CPU: 0 PID: 5477 Comm: syz-executor.0 Not tainted 6.7.0-rc2-syzkaller-00029-g9b6de136b5f0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
RIP: 0010:fib6_add+0x310d/0x3fa0 net/ipv6/ip6_fib.c:1516
Code: 00 48 8b 54 24 68 e8 42 22 00 00 48 85 c0 74 14 49 89 c6 e8 d5 d3 c2 f7 eb 5d e8 ce d3 c2 f7 e9 ca 00 00 00 e8 c4 d3 c2 f7 90 <0f> 0b 90 48 b8 00 00 00 00 00 fc ff df 48 8b 4c 24 38 80 3c 01 00
RSP: 0018:ffffc90005067740 EFLAGS: 00010293
RAX: ffffffff89cba5bc RBX: ffffc90005067ab0 RCX: ffff88801a2e9dc0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90005067980 R08: ffffffff89cbca85 R09: 1ffff110040d4b85
R10: dffffc0000000000 R11: ffffed10040d4b86 R12: 00000000ffffffff
R13: 1ffff110051c3904 R14: ffff8880206a5c00 R15: ffff888028e1c820
FS: 00007f763783c6c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f763783bff8 CR3: 000000007f74d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__ip6_ins_rt net/ipv6/route.c:1303 [inline]
ip6_route_add+0x88/0x120 net/ipv6/route.c:3847
ipv6_route_ioctl+0x525/0x7b0 net/ipv6/route.c:4467
inet6_ioctl+0x21a/0x270 net/ipv6/af_inet6.c:575
sock_do_ioctl+0x152/0x460 net/socket.c:1220
sock_ioctl+0x615/0x8c0 net/socket.c:1339
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x45/0x110 arch/x86/entry/common.c:82
Fixes: 7bbfe00e0252 ("ipv6: fix general protection fault in fib6_add()")
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Wei Wang <weiwan@xxxxxxxxxx>
Reviewed-by: David Ahern <dsahern@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20231129160630.3509216-1-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 5ff67cb8b6ace..92bc56028b8b6 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1351,13 +1351,9 @@ int fib6_add(struct fib6_node *root, struct fib6_info *rt,
if (!pn_leaf && !(pn->fn_flags & RTN_RTINFO)) {
pn_leaf = fib6_find_prefix(info->nl_net, table,
pn);
-#if RT6_DEBUG >= 2
- if (!pn_leaf) {
- WARN_ON(!pn_leaf);
+ if (!pn_leaf)
pn_leaf =
info->nl_net->ipv6.fib6_null_entry;
- }
-#endif
fib6_info_hold(pn_leaf);
rcu_assign_pointer(pn->leaf, pn_leaf);
}
