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| author | Eric W. Biederman <ebiederm@xmission.com> | 2018-03-28 20:38:55 +0200 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2018-03-28 23:40:08 +0200 |
| commit | 2236d4d39035b9839944603ec4b65ce71180a9ea (patch) | |
| tree | 49022c8b20f98d94bc4a4df4c0e3f5f07ab22e81 | |
| parent | ipc/shm: fix up for struct file no longer being available in shm.h (diff) | |
| download | linux-2236d4d39035b9839944603ec4b65ce71180a9ea.tar.xz linux-2236d4d39035b9839944603ec4b65ce71180a9ea.zip | |
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>
| -rw-r--r-- | ipc/shm.c | 4 |
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; } |