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| author | Manfred Spraul <manfred@colorfullife.com> | 2018-08-21 22:01:21 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-08-22 10:52:51 -0700 |
| commit | 615c999cd8a07b7c3c93bbdee89ef705d2ce52e1 (patch) | |
| tree | 9a61d371b17498dead9ff9136ebd25402bab82fa /ipc/shm.c | |
| parent | 5cb366bb3a746f6b06ea086b322e21e345401c9d (diff) | |
| download | linux-615c999cd8a07b7c3c93bbdee89ef705d2ce52e1.tar.gz | |
ipc: compute kern_ipc_perm.id under the ipc lock
ipc_addid() initializes kern_ipc_perm.id after having called ipc_idr_alloc(). Thus a parallel semctl() or msgctl() that uses e.g. MSG_STAT may use this unitialized value as the return code. The patch moves all accesses to kern_ipc_perm.id under the spin_lock(). The issues is related to the finding of syzbot+2827ef6b3385deb07eaf@syzkaller.appspotmail.com: syzbot found an issue with kern_ipc_perm.seq Link: http://lkml.kernel.org/r/20180712185241.4017-2-manfred@colorfullife.com Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Reviewed-by: Davidlohr Bueso <dbueso@suse.de> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/shm.c')
| -rw-r--r-- | ipc/shm.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index b204feb38274..b3b089315d3b 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -962,7 +962,6 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid, int cmd, struct shmid64_ds *tbuf) { struct shmid_kernel *shp; - int id = 0; int err; memset(tbuf, 0, sizeof(*tbuf)); @@ -974,7 +973,6 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid, err = PTR_ERR(shp); goto out_unlock; } - id = shp->shm_perm.id; } else { /* IPC_STAT */ shp = shm_obtain_object_check(ns, shmid); if (IS_ERR(shp)) { @@ -1024,10 +1022,21 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid, tbuf->shm_lpid = pid_vnr(shp->shm_lprid); tbuf->shm_nattch = shp->shm_nattch; - ipc_unlock_object(&shp->shm_perm); - rcu_read_unlock(); - return id; + if (cmd == IPC_STAT) { + /* + * As defined in SUS: + * Return 0 on success + */ + err = 0; + } else { + /* + * SHM_STAT and SHM_STAT_ANY (both Linux specific) + * Return the full id, including the sequence number + */ + err = shp->shm_perm.id; + } + ipc_unlock_object(&shp->shm_perm); out_unlock: rcu_read_unlock(); return err; |