+ prctl-move-pr_get_auxv-out-of-pr_mce_kill.patch added to mm-hotfixes-unstable branch

+ prctl-move-pr_get_auxv-out-of-pr_mce_kill.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: prctl: move PR_GET_AUXV out of PR_MCE_KILL
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     prctl-move-pr_get_auxv-out-of-pr_mce_kill.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/prctl-move-pr_get_auxv-out-of-pr_mce_kill.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Miguel Ojeda <ojeda@kernel.org>
Subject: prctl: move PR_GET_AUXV out of PR_MCE_KILL
Date: Sun, 9 Jul 2023 01:33:44 +0200

Somehow PR_GET_AUXV got added into PR_MCE_KILL's switch when the patch was
applied [1].

Thus move it out of the switch, to the place the patch added it.

In the recently released v6.4 kernel some user could, in principle, be
already using this feature by mapping the right page and passing the
PR_GET_AUXV constant as a pointer:

    prctl(PR_MCE_KILL, PR_GET_AUXV, ...)

So this does change the behavior for users.  We could keep the bug since
the other subcases in PR_MCE_KILL (PR_MCE_KILL_CLEAR and PR_MCE_KILL_SET)
do not overlap.

However, v6.4 may be recent enough (2 weeks old) that moving the lines
(rather than just adding a new case) does not break anybody?  Moreover,
the documentation in man-pages was just committed today [2].

Link: https://lkml.kernel.org/r/20230708233344.361854-1-ojeda@kernel.org
Fixes: ddc65971bb67 ("prctl: add PR_GET_AUXV to copy auxv to userspace")
Link: https://lore.kernel.org/all/d81864a7f7f43bca6afa2a09fc2e850e4050ab42.1680611394.git.josh@joshtriplett.org/ [1]
Link: https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=8cf0c06bfd3c2b219b044d4151c96f0da50af9ad [2]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/sys.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/kernel/sys.c~prctl-move-pr_get_auxv-out-of-pr_mce_kill
+++ a/kernel/sys.c
@@ -2535,11 +2535,6 @@ SYSCALL_DEFINE5(prctl, int, option, unsi
 			else
 				return -EINVAL;
 			break;
-	case PR_GET_AUXV:
-		if (arg4 || arg5)
-			return -EINVAL;
-		error = prctl_get_auxv((void __user *)arg2, arg3);
-		break;
 		default:
 			return -EINVAL;
 		}
@@ -2694,6 +2689,11 @@ SYSCALL_DEFINE5(prctl, int, option, unsi
 	case PR_SET_VMA:
 		error = prctl_set_vma(arg2, arg3, arg4, arg5);
 		break;
+	case PR_GET_AUXV:
+		if (arg4 || arg5)
+			return -EINVAL;
+		error = prctl_get_auxv((void __user *)arg2, arg3);
+		break;
 #ifdef CONFIG_KSM
 	case PR_SET_MEMORY_MERGE:
 		if (arg3 || arg4 || arg5)
_

Patches currently in -mm which might be from ojeda@kernel.org are

prctl-move-pr_get_auxv-out-of-pr_mce_kill.patch