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bsd-user, linux-user: signal: recursive signal delivery fix

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Synchronous signals must accommodate a synchronous signal being
raised during delivery, as asynchronous ones do. For example
badframe errors during delivery will cause SIGSEGV to be raised.

Without this fix, cpu_loop() runs process_pending_signals() which
delivers the first synchronous signal (e.g., SIGILL) which fails
to set the handler and forces SIGSEGV, but that is not picked up.
process_pending_signals() returns. Then cpu_loop() runs cpu_exec()
again, which attempts to execute the same instruction, another
SIGILL.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20260321135624.581398-3-npiggin@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Nicholas Piggin
2026-03-21 23:56:22 +10:00
committed by Peter Maydell
parent fa6dfcc373
commit 7e966ef38f
2 changed files with 12 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
bsd-user/signal.c
View File

@@ -998,7 +998,12 @@ void process_pending_signals(CPUArchState *env)
sigdelset(&ts->signal_mask, target_to_host_signal(sig)); sigdelset(&ts->signal_mask, target_to_host_signal(sig));
sigact_table[sig - 1]._sa_handler = TARGET_SIG_DFL; sigact_table[sig - 1]._sa_handler = TARGET_SIG_DFL;
} }
/*
* Restart scan from the beginning, as handle_pending_signal
* might have resulted in a new synchronous signal (eg SIGSEGV).
*/
handle_pending_signal(env, sig, &ts->sync_signal); handle_pending_signal(env, sig, &ts->sync_signal);
goto restart_scan;
} }
k = ts->sigtab; k = ts->sigtab;
@@ -1008,10 +1013,7 @@ void process_pending_signals(CPUArchState *env)
if (k->pending && if (k->pending &&
!sigismember(blocked_set, target_to_host_signal(sig))) { !sigismember(blocked_set, target_to_host_signal(sig))) {
handle_pending_signal(env, sig, k); handle_pending_signal(env, sig, k);
/* /* Restart scan, explained above. */
* Restart scan from the beginning, as handle_pending_signal
* might have resulted in a new synchronous signal (eg SIGSEGV).
*/
goto restart_scan; goto restart_scan;
} }
} }

9
linux-user/signal.c
View File

@@ -1384,6 +1384,11 @@ void process_pending_signals(CPUArchState *cpu_env)
} }
handle_pending_signal(cpu_env, sig, &ts->sync_signal); handle_pending_signal(cpu_env, sig, &ts->sync_signal);
/*
* Restart scan from the beginning, as handle_pending_signal
* might have resulted in a new synchronous signal (eg SIGSEGV).
*/
goto restart_scan;
} }
for (sig = 1; sig <= TARGET_NSIG; sig++) { for (sig = 1; sig <= TARGET_NSIG; sig++) {
@@ -1394,9 +1399,7 @@ void process_pending_signals(CPUArchState *cpu_env)
(!sigismember(blocked_set, (!sigismember(blocked_set,
target_to_host_signal_table[sig]))) { target_to_host_signal_table[sig]))) {
handle_pending_signal(cpu_env, sig, &ts->sigtab[sig - 1]); handle_pending_signal(cpu_env, sig, &ts->sigtab[sig - 1]);
/* Restart scan from the beginning, as handle_pending_signal /* Restart scan, explained above. */
* might have resulted in a new synchronous signal (eg SIGSEGV).
*/
goto restart_scan; goto restart_scan;
} }
} }