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signal/sh: Use force_sig(SIGKILL) instead of do_group_exit(SIGKILL)

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[ Upstream commit ce0ee4e6ac99606f3945f4d47775544edc3f7985 ]

Today the sh code allocates memory the first time a process uses
the fpu.  If that memory allocation fails, kill the affected task
with force_sig(SIGKILL) rather than do_group_exit(SIGKILL).

Calling do_group_exit from an exception handler can potentially lead
to dead locks as do_group_exit is not designed to be called from
interrupt context.  Instead use force_sig(SIGKILL) to kill the
userspace process.  Sending signals in general and force_sig in
particular has been tested from interrupt context so there should be
no problems.

Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: linux-sh@vger.kernel.org
Fixes: 0ea820cf9b ("sh: Move over to dynamically allocated FPU context.")
Link: https://lkml.kernel.org/r/20211020174406.17889-6-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Eric W. Biederman 2021-10-20 12:43:52 -05:00 committed by Greg Kroah-Hartman
parent 9e6985190f
commit 9770f8c29f
1 changed files with 6 additions and 4 deletions
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10
arch/sh/kernel/cpu/fpu.c
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@ -62,18 +62,20 @@ void fpu_state_restore(struct pt_regs *regs)
}
if (!tsk_used_math(tsk)) {
local_irq_enable();
int ret;
/*
* does a slab alloc which can sleep
*/
if (init_fpu(tsk)) {
local_irq_enable();
ret = init_fpu(tsk);
local_irq_disable();
if (ret) {
/*
* ran out of memory!
*/
do_group_exit(SIGKILL);
force_sig(SIGKILL);
return;
}
local_irq_disable();
}
grab_fpu(regs);