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x86/entry: Fix entry/exit mismatch on failed fast 32-bit syscalls 

commit 5d5675df79 upstream.

On a 32-bit fast syscall that fails to read its arguments from user
memory, the kernel currently does syscall exit work but not
syscall entry work.  This confuses audit and ptrace.  For example:

    $ ./tools/testing/selftests/x86/syscall_arg_fault_32
    ...
    strace: pid 264258: entering, ptrace_syscall_info.op == 2
    ...

This is a minimal fix intended for ease of backporting.  A more
complete cleanup is coming.

Fixes: 0b085e68f4 ("x86/entry: Consolidate 32/64 bit syscall entry")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/8c82296ddf803b91f8d1e5eac89e5803ba54ab0e.1614884673.git.luto@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/289/head^2
Andy Lutomirski 2021-03-04 11:05:54 -08:00 committed by Greg Kroah-Hartman
parent a2bab396cb
commit e40384fcd6
1 changed files with 2 additions and 1 deletions
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3
arch/x86/entry/common.c
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@ -128,7 +128,8 @@ static noinstr bool __do_fast_syscall_32(struct pt_regs *regs)
regs->ax = -EFAULT;
instrumentation_end();
syscall_exit_to_user_mode(regs);
local_irq_disable();
irqentry_exit_to_user_mode(regs);
return false;
}