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authorEric W. Biederman <ebiederm@xmission.com>2018-03-28 21:38:55 +0300
committerEric W. Biederman <ebiederm@xmission.com>2018-03-29 00:40:08 +0300
commit2236d4d39035b9839944603ec4b65ce71180a9ea (patch)
tree49022c8b20f98d94bc4a4df4c0e3f5f07ab22e81 /ipc
parent8ecd2953d0a1b78748b36f5bed6f233f5bd6d6ea (diff)
downloadlinux-2236d4d39035b9839944603ec4b65ce71180a9ea.tar.xz
ipc/shm: Fix pid freeing.
The 0day kernel test build report reported an oops: > > IP: put_pid+0x22/0x5c > PGD 19efa067 P4D 19efa067 PUD 0 > Oops: 0000 [#1] > CPU: 0 PID: 727 Comm: trinity Not tainted 4.16.0-rc2-00010-g98f929b #1 > RIP: 0010:put_pid+0x22/0x5c > RSP: 0018:ffff986719f73e48 EFLAGS: 00010202 > RAX: 00000006d765f710 RBX: ffff98671a4fa4d0 RCX: ffff986719f73d40 > RDX: 000000006f6e6125 RSI: 0000000000000000 RDI: ffffffffa01e6d21 > RBP: ffffffffa0955fe0 R08: 0000000000000020 R09: 0000000000000000 > R10: 0000000000000078 R11: ffff986719f73e76 R12: 0000000000001000 > R13: 00000000ffffffea R14: 0000000054000fb0 R15: 0000000000000000 > FS: 00000000028c2880(0000) GS:ffffffffa06ad000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000677846439 CR3: 0000000019fc1005 CR4: 00000000000606b0 > Call Trace: > ? ipc_update_pid+0x36/0x3e > ? newseg+0x34c/0x3a6 > ? ipcget+0x5d/0x528 > ? entry_SYSCALL_64_after_hwframe+0x52/0xb7 > ? SyS_shmget+0x5a/0x84 > ? do_syscall_64+0x194/0x1b3 > ? entry_SYSCALL_64_after_hwframe+0x42/0xb7 > Code: ff 05 e7 20 9b 03 58 c9 c3 48 ff 05 85 21 9b 03 48 85 ff 74 4f 8b 47 04 8b 17 48 ff 05 7c 21 9b 03 48 83 c0 03 48 c1 e0 04 ff ca <48> 8b 44 07 08 74 1f 48 ff 05 6c 21 9b 03 ff 0f 0f 94 c2 48 ff > RIP: put_pid+0x22/0x5c RSP: ffff986719f73e48 > CR2: 0000000677846439 > ---[ end trace ab8c5cb4389d37c5 ]--- > Kernel panic - not syncing: Fatal exception In newseg when changing shm_cprid and shm_lprid from pid_t to struct pid* I misread the kvmalloc as kvzalloc and thought shp was initialized to 0. As that is not the case it is not safe to for the error handling to address shm_cprid and shm_lprid before they are initialized. Therefore move the cleanup of shm_cprid and shm_lprid from the no_file error cleanup path to the no_id error cleanup path. Ensuring that an early error exit won't cause the oops above. Reported-by: kernel test robot <fengguang.wu@intel.com> Reviewed-by: Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/shm.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/ipc/shm.c b/ipc/shm.c
index 018db3d0e70e..35bdfe76d11b 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -646,12 +646,12 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
return error;
no_id:
+ ipc_update_pid(&shp->shm_cprid, NULL);
+ ipc_update_pid(&shp->shm_lprid, NULL);
if (is_file_hugepages(file) && shp->mlock_user)
user_shm_unlock(size, shp->mlock_user);
fput(file);
no_file:
- ipc_update_pid(&shp->shm_cprid, NULL);
- ipc_update_pid(&shp->shm_lprid, NULL);
call_rcu(&shp->shm_perm.rcu, shm_rcu_free);
return error;
}