Commit f68b2d5a authored by Tiwei Bie's avatar Tiwei Bie Committed by Johannes Berg
Browse files

um: Preserve errno within signal handler 



We rely on errno to determine whether a syscall has failed, so we
need to ensure that accessing errno is async-signal-safe. Currently,
we preserve the errno in sig_handler_common(), but it doesn't cover
every possible case. Let's do it in hard_handler() instead, which
is the signal handler we actually register.

Signed-off-by: default avatarTiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20260106001228.1531146-2-tiwei.btw@antgroup.com


Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 0f61b186

arch/um/os-Linux/signal.c

+3 −3
Original line number Diff line number Diff line
@@ -36,7 +36,6 @@ void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *, void *mc) = 
static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)

{

	struct uml_pt_regs r;

	int save_errno = errno;



	r.is_user = 0;

	if (sig == SIGSEGV) {
@@ -50,8 +49,6 @@ static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc) 
		unblock_signals_trace();



	(*sig_info[sig])(sig, si, &r, mc);



	errno = save_errno;

}



/*
@@ -207,8 +204,11 @@ static void hard_handler(int sig, siginfo_t *si, void *p) 
{

	ucontext_t *uc = p;

	mcontext_t *mc = &uc->uc_mcontext;

	int save_errno = errno;



	(*handlers[sig])(sig, (struct siginfo *)si, mc);



	errno = save_errno;

}



void set_handler(int sig)