diff options
| author | Eric Dumazet <edumazet@google.com> | 2019-05-29 15:36:10 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-05-30 14:52:14 -0700 |
| commit | a4270d6795b0580287453ea55974d948393e66ef (patch) | |
| tree | 9f3ac961e1c06d01e340e3eae2222d2bcc89a7d8 | |
| parent | c3bc6debb4c7555e7fb1b104ffda416e89570b50 (diff) | |
net-gro: fix use-after-free read in napi_gro_frags()
If a network driver provides to napi_gro_frags() an
skb with a page fragment of exactly 14 bytes, the call
to gro_pull_from_frag0() will 'consume' the fragment
by calling skb_frag_unref(skb, 0), and the page might
be freed and reused.
Reading eth->h_proto at the end of napi_frags_skb() might
read mangled data, or crash under specific debugging features.
BUG: KASAN: use-after-free in napi_frags_skb net/core/dev.c:5833 [inline]
BUG: KASAN: use-after-free in napi_gro_frags+0xc6f/0xd10 net/core/dev.c:5841
Read of size 2 at addr ffff88809366840c by task syz-executor599/8957
CPU: 1 PID: 8957 Comm: syz-executor599 Not tainted 5.2.0-rc1+ #32
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
__kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
kasan_report+0x12/0x20 mm/kasan/common.c:614
__asan_report_load_n_noabort+0xf/0x20 mm/kasan/generic_report.c:142
napi_frags_skb net/core/dev.c:5833 [inline]
napi_gro_frags+0xc6f/0xd10 net/core/dev.c:5841
tun_get_user+0x2f3c/0x3ff0 drivers/net/tun.c:1991
tun_chr_write_iter+0xbd/0x156 drivers/net/tun.c:2037
call_write_iter include/linux/fs.h:1872 [inline]
do_iter_readv_writev+0x5f8/0x8f0 fs/read_write.c:693
do_iter_write fs/read_write.c:970 [inline]
do_iter_write+0x184/0x610 fs/read_write.c:951
vfs_writev+0x1b3/0x2f0 fs/read_write.c:1015
do_writev+0x15b/0x330 fs/read_write.c:1058
Fixes: a50e233c50db ("net-gro: restore frag0 optimization")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/core/dev.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index cc2a4e257324..66f7508825bd 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5775,7 +5775,6 @@ static struct sk_buff *napi_frags_skb(struct napi_struct *napi) skb_reset_mac_header(skb); skb_gro_reset_offset(skb); - eth = skb_gro_header_fast(skb, 0); if (unlikely(skb_gro_header_hard(skb, hlen))) { eth = skb_gro_header_slow(skb, hlen, 0); if (unlikely(!eth)) { @@ -5785,6 +5784,7 @@ static struct sk_buff *napi_frags_skb(struct napi_struct *napi) return NULL; } } else { + eth = (const struct ethhdr *)skb->data; gro_pull_from_frag0(skb, hlen); NAPI_GRO_CB(skb)->frag0 += hlen; NAPI_GRO_CB(skb)->frag0_len -= hlen; |