2024-02-16 23:30:29

by Kees Cook

Subject: [PATCH] enic: Avoid false positive under FORTIFY_SOURCE

FORTIFY_SOURCE has been ignoring 0-sized destinations while the kernel
code base has been converted to flexible arrays. In order to enforce
the 0-sized destinations (e.g. with __counted_by), the remaining 0-sized
destinations need to be handled. Unfortunately, struct vic_provinfo
resists full conversion, as it contains a flexible array of flexible
arrays, which is only possible with the 0-sized fake flexible array.

Use unsafe_memcpy() to avoid future false positives under
CONFIG_FORTIFY_SOURCE.

Signed-off-by: Kees Cook <[email protected]>
---
Cc: Christian Benvenuti <[email protected]>
Cc: Satish Kharat <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: Gustavo A. R. Silva <[email protected]>
Cc: [email protected]
---
drivers/net/ethernet/cisco/enic/vnic_vic.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cisco/enic/vnic_vic.c b/drivers/net/ethernet/cisco/enic/vnic_vic.c
index 20fcb20b42ed..66b577835338 100644
--- a/drivers/net/ethernet/cisco/enic/vnic_vic.c
+++ b/drivers/net/ethernet/cisco/enic/vnic_vic.c
@@ -49,7 +49,8 @@ int vic_provinfo_add_tlv(struct vic_provinfo *vp, u16 type, u16 length,

tlv->type = htons(type);
tlv->length = htons(length);
- memcpy(tlv->value, value, length);
+ unsafe_memcpy(tlv->value, value, length,
+ /* Flexible array of flexible arrays */);

vp->num_tlvs = htonl(ntohl(vp->num_tlvs) + 1);
vp->length = htonl(ntohl(vp->length) +
--
2.34.1

2024-02-19 11:01:05

by patchwork-bot+netdevbpf

Subject: Re: [PATCH] enic: Avoid false positive under FORTIFY_SOURCE

Hello:

This patch was applied to netdev/net.git (main)
by David S. Miller <[email protected]>:

On Fri, 16 Feb 2024 15:30:05 -0800 you wrote:
> FORTIFY_SOURCE has been ignoring 0-sized destinations while the kernel
> code base has been converted to flexible arrays. In order to enforce
> the 0-sized destinations (e.g. with __counted_by), the remaining 0-sized
> destinations need to be handled. Unfortunately, struct vic_provinfo
> resists full conversion, as it contains a flexible array of flexible
> arrays, which is only possible with the 0-sized fake flexible array.
>
> [...]

Here is the summary with links:
- enic: Avoid false positive under FORTIFY_SOURCE
https://git.kernel.org/netdev/net/c/40b9385dd8e6

You are awesome, thank you!
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