From: "Eric W. Biederman" ebiederm@xmission.com
stable inclusion from stable-5.10.80 commit a4cbf00e5ab8022f45ffc93c10feced1b2334892 bugzilla: 185821 https://gitee.com/openeuler/kernel/issues/I4L7CG
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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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: 0ea820cf9bf5 ("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 Signed-off-by: Chen Jun chenjun102@huawei.com Reviewed-by: Weilong Chen chenweilong@huawei.com Acked-by: Weilong Chen chenweilong@huawei.com
Signed-off-by: Chen Jun chenjun102@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- arch/sh/kernel/cpu/fpu.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/arch/sh/kernel/cpu/fpu.c b/arch/sh/kernel/cpu/fpu.c index ae354a2931e7..fd6db0ab1928 100644 --- a/arch/sh/kernel/cpu/fpu.c +++ b/arch/sh/kernel/cpu/fpu.c @@ -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);