[PATCH net-next] scm: fix a typo in put_cmsg()

[PATCH net-next] scm: fix a typo in put_cmsg()

[Eric Dumazet]

From: Eric Dumazet <edumazet@google.com>

We need to store cmlen instead of len in cm->cmsg_len.

Fixes: 38ebcf5096a8 ("scm: optimize put_cmsg()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Jakub Kicinski <kuba@kernel.org>
---
 net/core/scm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/scm.c b/net/core/scm.c
index bd96c922041d22a2f3b7ee73e4b3183316f9b616..ae3085d9aae8adb81d3bb42c8a915a205476a0ee 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -232,7 +232,7 @@ int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
 		if (!user_write_access_begin(cm, cmlen))
 			goto efault;
 
-		unsafe_put_user(len, &cm->cmsg_len, efault_end);
+		unsafe_put_user(cmlen, &cm->cmsg_len, efault_end);
 		unsafe_put_user(level, &cm->cmsg_level, efault_end);
 		unsafe_put_user(type, &cm->cmsg_type, efault_end);
 		unsafe_copy_to_user(CMSG_USER_DATA(cm), data,
-- 
2.31.1.368.gbe11c130af-goog

Re: [PATCH net-next] scm: fix a typo in put_cmsg()

[Ido Schimmel]

On Fri, Apr 16, 2021 at 11:35:38AM -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> We need to store cmlen instead of len in cm->cmsg_len.
> 
> Fixes: 38ebcf5096a8 ("scm: optimize put_cmsg()")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Jakub Kicinski <kuba@kernel.org>

Tested-by: Ido Schimmel <idosch@nvidia.com>

(I was about to bisect, but then noticed the report from Jakub)

Thanks!

Re: [PATCH net-next] scm: fix a typo in put_cmsg()

[Jakub Kicinski]

On Fri, 16 Apr 2021 11:35:38 -0700 Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> We need to store cmlen instead of len in cm->cmsg_len.
> 
> Fixes: 38ebcf5096a8 ("scm: optimize put_cmsg()")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Jakub Kicinski <kuba@kernel.org>

FWIW can confirm it fixes the issue:

Tested-by: Jakub Kicinski <kuba@kernel.org>

Thanks!

Re: [PATCH net-next] scm: fix a typo in put_cmsg()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (refs/heads/master):

On Fri, 16 Apr 2021 11:35:38 -0700 you wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> We need to store cmlen instead of len in cm->cmsg_len.
> 
> Fixes: 38ebcf5096a8 ("scm: optimize put_cmsg()")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Jakub Kicinski <kuba@kernel.org>
> 
> [...]

Here is the summary with links:
  - [net-next] scm: fix a typo in put_cmsg()
    https://git.kernel.org/netdev/net-next/c/e7ad33fa7bc5

You are awesome, thank you!
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