summaryrefslogtreecommitdiff
path: root/net
diff options
context:
space:
mode:
authorTadeusz Struk <tadeusz.struk@linaro.org>2022-03-11 02:25:38 +0300
committerJakub Kicinski <kuba@kernel.org>2022-03-12 04:11:38 +0300
commit5e34af4142ffe68f01c8a9acae83300f8911e20c (patch)
treebb1d7d9398f866ca1a2264e7a1118ef638501381 /net
parent186d32bbf034417b40e2b4e773eeb8ef106c16c1 (diff)
downloadlinux-5e34af4142ffe68f01c8a9acae83300f8911e20c.tar.xz
net: ipv6: fix skb_over_panic in __ip6_append_data
Syzbot found a kernel bug in the ipv6 stack: LINK: https://syzkaller.appspot.com/bug?id=205d6f11d72329ab8d62a610c44c5e7e25415580 The reproducer triggers it by sending a crafted message via sendmmsg() call, which triggers skb_over_panic, and crashes the kernel: skbuff: skb_over_panic: text:ffffffff84647fb4 len:65575 put:65575 head:ffff888109ff0000 data:ffff888109ff0088 tail:0x100af end:0xfec0 dev:<NULL> Update the check that prevents an invalid packet with MTU equal to the fregment header size to eat up all the space for payload. The reproducer can be found here: LINK: https://syzkaller.appspot.com/text?tag=ReproC&x=1648c83fb00000 Reported-by: syzbot+e223cf47ec8ae183f2a0@syzkaller.appspotmail.com Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org> Acked-by: Willem de Bruijn <willemb@google.com> Link: https://lore.kernel.org/r/20220310232538.1044947-1-tadeusz.struk@linaro.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
-rw-r--r--net/ipv6/ip6_output.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 4788f6b37053..194832663d85 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1476,8 +1476,8 @@ static int __ip6_append_data(struct sock *sk,
sizeof(struct frag_hdr) : 0) +
rt->rt6i_nfheader_len;
- if (mtu < fragheaderlen ||
- ((mtu - fragheaderlen) & ~7) + fragheaderlen < sizeof(struct frag_hdr))
+ if (mtu <= fragheaderlen ||
+ ((mtu - fragheaderlen) & ~7) + fragheaderlen <= sizeof(struct frag_hdr))
goto emsgsize;
maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen -