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| author | Philippe Mikoyan <philippe.mikoyan@skat.systems> | 2018-02-06 15:40:49 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-02-06 18:32:46 -0800 |
| commit | 87ad4b0d853e8a65d6002f4e7bd3dce4ae3a52da (patch) | |
| tree | c1e7faec69a13a77606fd6e8c9578080ffe531e1 /ipc/shm.c | |
| parent | bac7a1fff7926fb9891a18fe33650884b0e13e41 (diff) | |
| download | linux-rpi3-87ad4b0d853e8a65d6002f4e7bd3dce4ae3a52da.tar.gz linux-rpi3-87ad4b0d853e8a65d6002f4e7bd3dce4ae3a52da.tar.bz2 linux-rpi3-87ad4b0d853e8a65d6002f4e7bd3dce4ae3a52da.zip | |
ipc: fix ipc data structures inconsistency
As described in the title, this patch fixes <ipc>id_ds inconsistency when
<ipc>ctl_stat executes concurrently with some ds-changing function, e.g.
shmat, msgsnd or whatever.
For instance, if shmctl(IPC_STAT) is running concurrently
with shmat, following data structure can be returned:
{... shm_lpid = 0, shm_nattch = 1, ...}
Link: http://lkml.kernel.org/r/20171202153456.6514-1-philippe.mikoyan@skat.systems
Signed-off-by: Philippe Mikoyan <philippe.mikoyan@skat.systems>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Manfred Spraul <manfred@colorfullife.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 | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index 7acda23430aa..4643865e9171 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -909,9 +909,11 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid, int cmd, struct shmid64_ds *tbuf) { struct shmid_kernel *shp; - int result; + int id = 0; int err; + memset(tbuf, 0, sizeof(*tbuf)); + rcu_read_lock(); if (cmd == SHM_STAT) { shp = shm_obtain_object(ns, shmid); @@ -919,14 +921,13 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid, err = PTR_ERR(shp); goto out_unlock; } - result = shp->shm_perm.id; + id = shp->shm_perm.id; } else { shp = shm_obtain_object_check(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); goto out_unlock; } - result = 0; } err = -EACCES; @@ -937,7 +938,14 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid, if (err) goto out_unlock; - memset(tbuf, 0, sizeof(*tbuf)); + ipc_lock_object(&shp->shm_perm); + + if (!ipc_valid_object(&shp->shm_perm)) { + ipc_unlock_object(&shp->shm_perm); + err = -EIDRM; + goto out_unlock; + } + kernel_to_ipc64_perm(&shp->shm_perm, &tbuf->shm_perm); tbuf->shm_segsz = shp->shm_segsz; tbuf->shm_atime = shp->shm_atim; @@ -946,8 +954,10 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid, tbuf->shm_cpid = shp->shm_cprid; tbuf->shm_lpid = shp->shm_lprid; tbuf->shm_nattch = shp->shm_nattch; + + ipc_unlock_object(&shp->shm_perm); rcu_read_unlock(); - return result; + return id; out_unlock: rcu_read_unlock(); |