FAILED: patch "[PATCH] kunit: kasan_test: disable fortify string checker on" 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 7a19afee6fb39df63ddea7ce78976d8c521178c6
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025090617-define-clerical-52ff@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 7a19afee6fb39df63ddea7ce78976d8c521178c6 Mon Sep 17 00:00:00 2001
From: Yeoreum Yun <[email protected]>
Date: Fri, 1 Aug 2025 13:02:36 +0100
Subject: [PATCH] kunit: kasan_test: disable fortify string checker on
kasan_strings() test

Similar to commit 09c6304e38e4 ("kasan: test: fix compatibility with FORTIFY_SOURCE") the kernel is panicing in kasan_string().

This is due to the src and ptr not being hidden from the optimizer which would disable the runtime fortify string checker.

Call trace:
  __fortify_panic+0x10/0x20 (P)
  kasan_strings+0x980/0x9b0
  kunit_try_run_case+0x68/0x190
  kunit_generic_run_threadfn_adapter+0x34/0x68
  kthread+0x1c4/0x228
  ret_from_fork+0x10/0x20
 Code: d503233f a9bf7bfd 910003fd 9424b243 (d4210000)
 ---[ end trace 0000000000000000 ]---
 note: kunit_try_catch[128] exited with irqs disabled
 note: kunit_try_catch[128] exited with preempt_count 1
     # kasan_strings: try faulted: last

** replaying previous printk message **
# kasan_strings: try faulted: last line seen mm/kasan/kasan_test_c.c:1600 # kasan_strings: internal error occurred preventing test case from running: -4

index e0968acc03aa..f4b17984b627 100644
@@ -1578,9 +1578,11 @@ static void kasan_strings(struct kunit *test)
 
 	ptr = kmalloc(size, GFP_KERNEL | __GFP_ZERO);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+	OPTIMIZER_HIDE_VAR(ptr);
 
 	src = kmalloc(KASAN_GRANULE_SIZE, GFP_KERNEL | __GFP_ZERO);
 	strscpy(src, "f0cacc1a0000000", KASAN_GRANULE_SIZE);
+	OPTIMIZER_HIDE_VAR(src);
 
 	/*
 	 * Make sure that strscpy() does not trigger KASAN if it overreads into

Similar to commit 09c6304e38e4 ("kasan: test: fix compatibility with FORTIFY_SOURCE") the kernel is panicing in kasan_string().

This is due to the src and ptr not being hidden from the optimizer which would disable the runtime fortify string checker.

Call trace:
  __fortify_panic+0x10/0x20 (P)
  kasan_strings+0x980/0x9b0
  kunit_try_run_case+0x68/0x190
  kunit_generic_run_threadfn_adapter+0x34/0x68
  kthread+0x1c4/0x228
  ret_from_fork+0x10/0x20
 Code: d503233f a9bf7bfd 910003fd 9424b243 (d4210000)
 ---[ end trace 0000000000000000 ]---
 note: kunit_try_catch[128] exited with irqs disabled
 note: kunit_try_catch[128] exited with preempt_count 1
     # kasan_strings: try faulted: last

** replaying previous printk message **
# kasan_strings: try faulted: last line seen mm/kasan/kasan_test_c.c:1600 # kasan_strings: internal error occurred preventing test case from running: -4

---
 lib/test_kasan.c | 1 +
 1 file changed, 1 insertion(+)

index ffedc34714ba..70b567d03316 100644
@@ -917,6 +917,7 @@ static void kasan_strings(struct kunit *test)
 
 	ptr = kmalloc(size, GFP_KERNEL | __GFP_ZERO);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+	OPTIMIZER_HIDE_VAR(ptr);
 
 	kfree(ptr);
 

--
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}