core/entry: Respect syscall number rewrites

The transcript of the x86 entry code to the generic version failed to reload the syscall number from ptregs after ptrace and seccomp have run, which both can modify the syscall number in ptregs. It returns the original syscall number instead which is obviously not the right thing to do. Reload the syscall number to fix that. Fixes: 142781e ("entry: Provide generic syscall entry functionality") Reported-by: Kyle Huey <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Kyle Huey <[email protected]> Tested-by: Kees Cook <[email protected]> Acked-by: Kees Cook <[email protected]> Link: https://lore.kernel.org/r/[email protected]
simonjhall · Aug 21, 2020 · d88d59b · d88d59b
1 parent 9123e3a
commit d88d59b
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
@@ -65,7 +65,8 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
 
 	syscall_enter_audit(regs, syscall);
 
-	return ret ? : syscall;
+	/* The above might have changed the syscall number */
+	return ret ? : syscall_get_nr(current, regs);
 }
 
 noinstr long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)