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| author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2020-03-03 14:59:13 -0300 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2020-03-05 14:40:28 -0300 |
| commit | 24fdebe75f6df4c0edacb3f0cdc030913920aa4c (patch) | |
| tree | 93fb399c11b914da400ce6f2a08c10b79e939eac /sysdeps/unix/sysv/linux/shmctl.c | |
| parent | d5e492ba4ced4a9101f82dbbd9de77223b9932ac (diff) | |
| download | glibc-24fdebe75f6df4c0edacb3f0cdc030913920aa4c.tar.gz | |
linux: Clear mode_t padding bits (BZ#25623)
The kernel might not clear the padding value for the ipc_perm mode
fields in compat mode (32 bit running on a 64 bit kernel). It was
fixed on v4.14 when the ipc compat code was refactored to move
(commits 553f770ef71b, 469391684626, c0ebccb6fa1e).
Although it is most likely a kernel issue, it was shown only due
BZ#18231 fix which made all the SysVIPC mode_t 32-bit regardless of
the kABI.
This patch fixes it by explicitly zeroing the upper bits for such
cases. The __ASSUME_SYSVIPC_BROKEN_MODE_T case already handles
it with the shift.
(The aarch64 ipc_priv.h is superflous since
__ASSUME_SYSVIPC_DEFAULT_IPC_64 is now defined as default).
Checked on i686-linux-gnu on 3.10 and on 4.15 kernel.
Diffstat (limited to 'sysdeps/unix/sysv/linux/shmctl.c')
| -rw-r--r-- | sysdeps/unix/sysv/linux/shmctl.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/sysdeps/unix/sysv/linux/shmctl.c b/sysdeps/unix/sysv/linux/shmctl.c index 39fa861e17..aed9e5260e 100644 --- a/sysdeps/unix/sysv/linux/shmctl.c +++ b/sysdeps/unix/sysv/linux/shmctl.c @@ -63,7 +63,6 @@ __new_shmctl (int shmid, int cmd, struct shmid_ds *buf) int ret = shmctl_syscall (shmid, cmd, buf); -#ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T if (ret >= 0) { switch (cmd) @@ -71,10 +70,16 @@ __new_shmctl (int shmid, int cmd, struct shmid_ds *buf) case IPC_STAT: case SHM_STAT: case SHM_STAT_ANY: +#ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T buf->shm_perm.mode >>= 16; +#else + /* Old Linux kernel versions might not clear the mode padding. */ + if (sizeof ((struct shmid_ds){0}.shm_perm.mode) + != sizeof (__kernel_mode_t)) + buf->shm_perm.mode &= 0xFFFF; +#endif } } -#endif return ret; } |