From be6b5ff4507197e98be54a2ab9106dfc1399ff8d Mon Sep 17 00:00:00 2001 From: Shuhao Fu Date: Thu, 28 Aug 2025 02:24:19 +0800 Subject: [PATCH] fs/smb: Fix inconsistent refcnt update stable inclusion from stable-v6.6.104 commit 4191ea1f0bb3e27d65c5dcde7bd00e709ec67141 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICYBJ5 CVE: CVE-2025-39819 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4191ea1f0bb3e27d65c5dcde7bd00e709ec67141 -------------------------------- commit ab529e6ca1f67bcf31f3ea80c72bffde2e9e053e upstream. 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 Acked-by: Paulo Alcantara (Red Hat) Cc: stable@vger.kernel.org Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman Signed-off-by: Qingshuang Fu --- 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); -- Gitee