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Fix races in setXid implementation.

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This commit is contained in:
Daniel Jacobowitz
2009-10-30 01:00:44 -07:00
committed by Ulrich Drepper
parent 31c759bf37
commit 25db0f6ca9
3 changed files with 125 additions and 26 deletions
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16
nptl/nptl-init.c
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@ -240,17 +240,23 @@ sighandler_setxid (int sig, siginfo_t *si, void *ctx)
INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0],
__xidcmd->id[1], __xidcmd->id[2]);
if (atomic_decrement_val (&__xidcmd->cntr) == 0)
lll_futex_wake (&__xidcmd->cntr, 1, LLL_PRIVATE);
/* Reset the SETXID flag. */
struct pthread *self = THREAD_SELF;
int flags = THREAD_GETMEM (self, cancelhandling);
THREAD_SETMEM (self, cancelhandling, flags & ~SETXID_BITMASK);
int flags, newval;
do
{
flags = THREAD_GETMEM (self, cancelhandling);
newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
flags & ~SETXID_BITMASK, flags);
}
while (flags != newval);
/* And release the futex. */
self->setxid_futex = 1;
lll_futex_wake (&self->setxid_futex, 1, LLL_PRIVATE);
if (atomic_decrement_val (&__xidcmd->cntr) == 0)
lll_futex_wake (&__xidcmd->cntr, 1, LLL_PRIVATE);
}