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Code Issues Releases Wiki Activity

futex: Fix hardcoded flags 

Xi reported that commit 5694289ce1 ("futex: Flag conversion") broke
glibc's robust futex tests.

This was narrowed down to the change of FLAGS_SHARED from 0x01 to
0x10, at which point Florian noted that handle_futex_death() has a
hardcoded flags argument of 1.

Change this to: FLAGS_SIZE_32 | FLAGS_SHARED, matching how
futex_to_flags() unconditionally sets FLAGS_SIZE_32 for all legacy
futex ops.

Reported-by: Xi Ruoyao <xry111@xry111.site>
Reported-by: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20231114201402.GA25315@noisy.programming.kicks-ass.net
Fixes: 5694289ce1 ("futex: Flag conversion")
Cc: <stable@vger.kernel.org>
This commit is contained in:
Peter Zijlstra 2023-11-14 21:36:13 +01:00 committed by Ingo Molnar
parent b85ea95d08
commit c9bd1568d5
1 changed files with 6 additions and 3 deletions
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9
kernel/futex/core.c
View File

@ -700,7 +700,8 @@ retry:
owner = uval & FUTEX_TID_MASK;
if (pending_op && !pi && !owner) {
futex_wake(uaddr, 1, 1, FUTEX_BITSET_MATCH_ANY);
futex_wake(uaddr, FLAGS_SIZE_32 | FLAGS_SHARED, 1,
FUTEX_BITSET_MATCH_ANY);
return 0;
}
@ -752,8 +753,10 @@ retry:
* Wake robust non-PI futexes here. The wakeup of
* PI futexes happens in exit_pi_state():
*/
if (!pi && (uval & FUTEX_WAITERS))
futex_wake(uaddr, 1, 1, FUTEX_BITSET_MATCH_ANY);
if (!pi && (uval & FUTEX_WAITERS)) {
futex_wake(uaddr, FLAGS_SIZE_32 | FLAGS_SHARED, 1,
FUTEX_BITSET_MATCH_ANY);
}
return 0;
}