diff mbox series

[v3] Fix error handling in begin_new_exec

Message ID AS8P193MB128517ADB5EFF29E04389EDAE4752@AS8P193MB1285.EURP193.PROD.OUTLOOK.COM (mailing list archive)
State New, archived
Headers show
Series [v3] Fix error handling in begin_new_exec | expand

Commit Message

Bernd Edlinger Jan. 22, 2024, 6:34 p.m. UTC 
If get_unused_fd_flags() fails, the error handling is incomplete
because bprm->cred is already set to NULL, and therefore
free_bprm will not unlock the cred_guard_mutex.
Note there are two error conditions which end up here,
one before and one after bprm->cred is cleared.

Fixes: b8a61c9e7b4a ("exec: Generic execfd support")
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 fs/exec.c | 3 +++
 1 file changed, 3 insertions(+)

v2: rebased to v6.7, retested and updated the commit message
to fix a checkpatch.pl style nit about the too short sha1 hash
in the Fixes: statement.
And retained Eric's Acked-by from:
https://lore.kernel.org/lkml/87mts2kcrm.fsf@disp2133/

v3: removed empty lines after Fixes: and Signed-off-by: header.


Thanks
Bernd.

Comments

Kees Cook Jan. 22, 2024, 8:53 p.m. UTC | #1 
On Mon, 22 Jan 2024 19:34:21 +0100, Bernd Edlinger wrote:
> If get_unused_fd_flags() fails, the error handling is incomplete
> because bprm->cred is already set to NULL, and therefore
> free_bprm will not unlock the cred_guard_mutex.
> Note there are two error conditions which end up here,
> one before and one after bprm->cred is cleared.
> 
> 
> [...]

Applied to for-next/execve, thanks!

[1/1] Fix error handling in begin_new_exec
      https://git.kernel.org/kees/c/84c39ec57d40

Take care,
diff mbox series

Patch

diff --git a/fs/exec.c b/fs/exec.c
index 8cdd5b2dd09c..e88249a1ce07 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1409,6 +1409,9 @@  int begin_new_exec(struct linux_binprm * bprm)
 
 out_unlock:
 	up_write(&me->signal->exec_update_lock);
+	if (!bprm->cred)
+		mutex_unlock(&me->signal->cred_guard_mutex);
+
 out:
 	return retval;
 }