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| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2021-07-26 14:52:51 -0500 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-07-26 23:02:17 +0100 |
| commit | 6321c7acb82872ef6576c520b0e178eaad3a25c0 (patch) | |
| tree | 9811ce28fc4ab78c11d3513f51aaac5233bf3e74 /net/ipv4/ip_output.c | |
| parent | 22171146f84ba57db44071de60ad44cfe634574a (diff) | |
| download | lwn-6321c7acb82872ef6576c520b0e178eaad3a25c0.tar.gz lwn-6321c7acb82872ef6576c520b0e178eaad3a25c0.zip | |
ipv4: ip_output.c: Fix out-of-bounds warning in ip_copy_addrs()
Fix the following out-of-bounds warning:
In function 'ip_copy_addrs',
inlined from '__ip_queue_xmit' at net/ipv4/ip_output.c:517:2:
net/ipv4/ip_output.c:449:2: warning: 'memcpy' offset [40, 43] from the object at 'fl' is out of the bounds of referenced subobject 'saddr' with type 'unsigned int' at offset 36 [-Warray-bounds]
449 | memcpy(&iph->saddr, &fl4->saddr,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
450 | sizeof(fl4->saddr) + sizeof(fl4->daddr));
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The problem is that the original code is trying to copy data into a
couple of struct members adjacent to each other in a single call to
memcpy(). This causes a legitimate compiler warning because memcpy()
overruns the length of &iph->saddr and &fl4->saddr. As these are just
a couple of struct members, fix this by using direct assignments,
instead of memcpy().
This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().
Link: https://github.com/KSPP/linux/issues/109
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/d5ae2e65-1f18-2577-246f-bada7eee6ccd@intel.com/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ip_output.c')
| -rw-r--r-- | net/ipv4/ip_output.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 8d8a8da3ae7e..a202dcec0dc2 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -446,8 +446,9 @@ static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4) { BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) != offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr)); - memcpy(&iph->saddr, &fl4->saddr, - sizeof(fl4->saddr) + sizeof(fl4->daddr)); + + iph->saddr = fl4->saddr; + iph->daddr = fl4->daddr; } /* Note: skb->sk can be different from sk, in case of tunnels */ |