From: Shuhao Fu <sfual@cse.ust.hk> mainline inclusion from mainline-v6.17-rc4 commit ab529e6ca1f67bcf31f3ea80c72bffde2e9e053e category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/ICYBJ5 CVE: CVE-2025-39819 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- A possible inconsistent update of refcount was identified in `smb2_compound_op`. Such inconsistent update could lead to possible resource leaks. Why it is a possible bug: 1. In the comment section of the function, it clearly states that the reference to `cfile` should be dropped after calling this function. 2. Every control flow path would check and drop the reference to `cfile`, except the patched one. 3. Existing callers would not handle refcount update of `cfile` if -ENOMEM is returned. To fix the bug, an extra goto label "out" is added, to make sure that the cleanup logic would always be respected. As the problem is caused by the allocation failure of `vars`, the cleanup logic between label "finished" and "out" can be safely ignored. According to the definition of function `is_replayable_error`, the error code of "-ENOMEM" is not recoverable. Therefore, the replay logic also gets ignored. Signed-off-by: Shuhao Fu <sfual@cse.ust.hk> Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.org> Cc: stable@vger.kernel.org Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Yifan Qiao <qiaoyifan4@huawei.com> --- fs/smb/client/smb2inode.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/smb/client/smb2inode.c b/fs/smb/client/smb2inode.c index e1078a1decdf..0cc80f472432 100644 --- a/fs/smb/client/smb2inode.c +++ b/fs/smb/client/smb2inode.c @@ -206,8 +206,10 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon, server = cifs_pick_channel(ses); vars = kzalloc(sizeof(*vars), GFP_ATOMIC); - if (vars == NULL) - return -ENOMEM; + if (vars == NULL) { + rc = -ENOMEM; + goto out; + } rqst = &vars->rqst[0]; rsp_iov = &vars->rsp_iov[0]; @@ -828,6 +830,7 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon, smb2_should_replay(tcon, &retries, &cur_sleep)) goto replay_again; +out: if (cfile) cifsFileInfo_put(cfile); -- 2.39.2