The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: dabf017539988a9bfc40a38dbafd35c501bacc44 Gitweb: https://git.kernel.org/tip/dabf017539988a9bfc40a38dbafd35c501bacc44 Author: Andy Lutomirski luto@kernel.org AuthorDate: Thu, 04 Mar 2021 11:05:54 -08:00 Committer: Thomas Gleixner tglx@linutronix.de CommitterDate: Fri, 05 Mar 2021 11:10:13 +01:00
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: 0b085e68f407 ("x86/entry: Consolidate 32/64 bit syscall entry") Signed-off-by: Andy Lutomirski luto@kernel.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/8c82296ddf803b91f8d1e5eac89e5803ba54ab0e.161488467...
--- arch/x86/entry/common.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index a2433ae..4efd39a 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -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; }