FAILED: patch "[PATCH] selftests/mm: fix potential wild pointer access of getline" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 9f1d75a4ce04095afdb63d8e540092ff8151dacf
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026080518-nuptials-untaken-f165@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9f1d75a4ce04095afdb63d8e540092ff8151dacf Mon Sep 17 00:00:00 2001
From: Chris Gellermann <[email protected]>
Date: Wed, 22 Jul 2026 15:02:46 +0200
Subject: [PATCH] selftests/mm: fix potential wild pointer access of getline
 due to missing init

This is another occurrence of using getline where the code assumes that
getline allocates memory to store the line, but the pointer passed to it
is uninitialized and potentially a non-null pointer.  This violates the
Open Group Spec[1] and caused a segfault in a similar situation in
selftest/clone3/clone3_set_tid.  Fix it by initializing the line pointer
to NULL.

The issue has been found by simply grepping through the selftest code
after running into the issue in clone3_set_tid.  Whether it segfaults in
its current state is unknown to me.  But it's good to be addressed due to
defensive reasons.

Link: https://lore.kernel.org/[email protected]
Link: https://pubs.opengroup.org/onlinepubs/9799919799/functions/getline.html [1]
Fixes: 26b4224d9961 ("selftests: expanding more mlock selftest")
Signed-off-by: Chris Gellermann <[email protected]>
Acked-by: David Hildenbrand (arm) <[email protected]>
Reviewed-by: Lorenzo Stoakes <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

diff --git a/tools/testing/selftests/mm/mlock-random-test.c b/tools/testing/selftests/mm/mlock-random-test.c
index 9d349c151360..16294bc7dae6 100644
--- a/tools/testing/selftests/mm/mlock-random-test.c
+++ b/tools/testing/selftests/mm/mlock-random-test.c
@@ -84,7 +84,7 @@ int get_proc_locked_vm_size(void)
 int get_proc_page_size(unsigned long addr)
 {
 	FILE *smaps;
-	char *line;
+	char *line = NULL;
 	unsigned long mmupage_size = 0;
 	size_t size;