Commit 5d5675df authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Borislav Petkov

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

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: 0b085e68 ("x86/entry: Consolidate 32/64 bit syscall entry")
Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/8c82296ddf803b91f8d1e5eac89e5803ba54ab0e.1614884673.git.luto@kernel.org
parent b59cc976
......@@ -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;
}
......
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