ACK: [SRU][N][PATCH 0/1] CVE-2025-21887

[John Cabaj]

On 7/16/25 1:33 PM, Manuel Diewald wrote:
> https://ubuntu.com/security/CVE-2025-21887
> 
> SRU Justification:
> 
> [Impact]
> 
> In the Linux kernel, the following vulnerability has been resolved:
> 
> ovl: fix UAF in ovl_dentry_update_reval by moving dput() in ovl_link_up
> 
> The issue was caused by dput(upper) being called before
> ovl_dentry_update_reval(), while upper->d_flags was still accessed in
> ovl_dentry_remote(). Move dput(upper) after its last use to prevent
> use-after-free.
> 
> [Fix]
> 
> Plucky: Not affected
> Noble:  Clean cherry-pick from mainline
> Jammy:  Fixed with upstream stable update v5.15.179 (LP: #2106026)
> Focal:  Not affected
> Bionic: Not affected
> Xenial: Not affected
> Trusty: Not affected
> 
> [Test Plan]
> 
> Compile-tested only.
> 
> [Where problems could occur]
> 
> Problems with the patch would be limited to overlayfs and manifest as
> unexpected behavior involving files.
> 
> 
> Vasiliy Kovalev (1):
>    ovl: fix UAF in ovl_dentry_update_reval by moving dput() in
>      ovl_link_up
> 
>   fs/overlayfs/copy_up.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 

Acked-by: John Cabaj <john.cabaj at canonical.com>