diff options
author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2020-10-05 17:30:05 -0300 |
---|---|---|
committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2020-10-06 15:29:35 -0300 |
commit | 7a887dd537cd00fe3cdf42b788b3f0e3b430b0ed (patch) | |
tree | 2ce82095bd3f24a54af4980703cbb69cd5b7d155 /sysdeps/unix/sysv/linux/timer_gettime.c | |
parent | 862897d2addfacc2af85b571ebf5a82659455e8c (diff) | |
download | glibc-7a887dd537cd00fe3cdf42b788b3f0e3b430b0ed.zip glibc-7a887dd537cd00fe3cdf42b788b3f0e3b430b0ed.tar.gz glibc-7a887dd537cd00fe3cdf42b788b3f0e3b430b0ed.tar.bz2 |
posix: Fix -Warray-bounds instances building timer_create [BZ #26687]
GCC 11 -Warray-bounds triggers invalid warnings when building
Linux timer_create.c:
../sysdeps/unix/sysv/linux/timer_create.c: In function '__timer_create_new':
../sysdeps/unix/sysv/linux/timer_create.c:83:17: warning: array subscript 'struct timer[0]' is partly outside array bounds of 'unsigned char[8]' [-Warray-bounds]
83 | newp->sigev_notify = (evp != NULL
| ^~
../sysdeps/unix/sysv/linux/timer_create.c:59:47: note: referencing an object of size 8 allocated by 'malloc'
59 | struct timer *newp = (struct timer *) malloc (offsetof (struct timer,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
60 | thrfunc));
| ~~~~~~~~~
The struct allocated for !SIGEV_THREAD timers only requires two 'int'
fields (sigev_notify and ktimerid) and the offsetof trick tries minimize
the memory usage by only allocation the required size. However,
although the resulting size is suffice for !SIGEV_THREAD time, accessing
the partially allocated object is error-prone and UB.
This patch fixes both issues by embedding the information whether
the timer if a SIGEV_THREAD in the returned 'timer_t'. For
!SIGEV_THREAD, the resulting 'timer_t' is the returned kernel timer
identifer (kernel_timer_t), while for SIGEV_THREAD it uses the fact
malloc returns at least _Alignof (max_align_t) pointers plus that
valid kernel_timer_t are always positive to set MSB bit of the returned
'timer_t' to indicate the timer handles a SIGEV_THREAD.
It allows to remove the memory allocation for !SIGEV_THREAD and also
remove the 'sigev_notify' field from 'struct timer'.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Diffstat (limited to 'sysdeps/unix/sysv/linux/timer_gettime.c')
-rw-r--r-- | sysdeps/unix/sysv/linux/timer_gettime.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/sysdeps/unix/sysv/linux/timer_gettime.c b/sysdeps/unix/sysv/linux/timer_gettime.c index 5d31c7c..07b6309 100644 --- a/sysdeps/unix/sysv/linux/timer_gettime.c +++ b/sysdeps/unix/sysv/linux/timer_gettime.c @@ -26,18 +26,18 @@ int __timer_gettime64 (timer_t timerid, struct __itimerspec64 *value) { - struct timer *kt = (struct timer *) timerid; + kernel_timer_t ktimerid = timerid_to_kernel_timer (timerid); #ifndef __NR_timer_gettime64 # define __NR_timer_gettime64 __NR_timer_gettime #endif - int ret = INLINE_SYSCALL_CALL (timer_gettime64, kt->ktimerid, value); + int ret = INLINE_SYSCALL_CALL (timer_gettime64, ktimerid, value); #ifndef __ASSUME_TIME64_SYSCALLS if (ret == 0 || errno != ENOSYS) return ret; struct itimerspec its32; - ret = INLINE_SYSCALL_CALL (timer_gettime, kt->ktimerid, &its32); + ret = INLINE_SYSCALL_CALL (timer_gettime, ktimerid, &its32); if (ret == 0) { value->it_interval = valid_timespec_to_timespec64 (its32.it_interval); |