The patch below does not apply to the 6.12-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 stable@vger.kernel.org.

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-6.12.y git checkout FETCH_HEAD git cherry-pick -x 6ee9b3d84775944fb8c8a447961cd01274ac671c # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025071347-compel-crate-aeba@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 6ee9b3d84775944fb8c8a447961cd01274ac671c Mon Sep 17 00:00:00 2001 From: Yeoreum Yun yeoreum.yun@arm.com Date: Thu, 3 Jul 2025 19:10:18 +0100 Subject: [PATCH] kasan: remove kasan_find_vm_area() to prevent possible deadlock

find_vm_area() couldn't be called in atomic_context. If find_vm_area() is called to reports vm area information, kasan can trigger deadlock like:

CPU0 CPU1 vmalloc(); alloc_vmap_area(); spin_lock(&vn->busy.lock) spin_lock_bh(&some_lock); <interrupt occurs> <in softirq> spin_lock(&some_lock); <access invalid address> kasan_report(); print_report(); print_address_description(); kasan_find_vm_area(); find_vm_area(); spin_lock(&vn->busy.lock) // deadlock!

To prevent possible deadlock while kasan reports, remove kasan_find_vm_area().

Link: https://lkml.kernel.org/r/20250703181018.580833-1-yeoreum.yun@arm.com Fixes: c056a364e954 ("kasan: print virtual mapping info in reports") Signed-off-by: Yeoreum Yun yeoreum.yun@arm.com Reported-by: Yunseong Kim ysk@kzalloc.com Reviewed-by: Andrey Ryabinin ryabinin.a.a@gmail.com Cc: Alexander Potapenko glider@google.com Cc: Andrey Konovalov andreyknvl@gmail.com Cc: Byungchul Park byungchul@sk.com Cc: Dmitriy Vyukov dvyukov@google.com Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Cc: Steven Rostedt rostedt@goodmis.org Cc: Vincenzo Frascino vincenzo.frascino@arm.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org

diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 8357e1a33699..b0877035491f 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -370,36 +370,6 @@ static inline bool init_task_stack_addr(const void *addr) sizeof(init_thread_union.stack)); }

-/* - * This function is invoked with report_lock (a raw_spinlock) held. A - * PREEMPT_RT kernel cannot call find_vm_area() as it will acquire a sleeping - * rt_spinlock. - * - * For !RT kernel, the PROVE_RAW_LOCK_NESTING config option will print a - * lockdep warning for this raw_spinlock -> spinlock dependency. This config - * option is enabled by default to ensure better test coverage to expose this - * kind of RT kernel problem. This lockdep splat, however, can be suppressed - * by using DEFINE_WAIT_OVERRIDE_MAP() if it serves a useful purpose and the - * invalid PREEMPT_RT case has been taken care of. - */ -static inline struct vm_struct *kasan_find_vm_area(void *addr) -{ - static DEFINE_WAIT_OVERRIDE_MAP(vmalloc_map, LD_WAIT_SLEEP); - struct vm_struct *va; - - if (IS_ENABLED(CONFIG_PREEMPT_RT)) - return NULL; - - /* - * Suppress lockdep warning and fetch vmalloc area of the - * offending address. - */ - lock_map_acquire_try(&vmalloc_map); - va = find_vm_area(addr); - lock_map_release(&vmalloc_map); - return va; -} - static void print_address_description(void *addr, u8 tag, struct kasan_report_info *info) { @@ -429,19 +399,8 @@ static void print_address_description(void *addr, u8 tag, }

if (is_vmalloc_addr(addr)) { - struct vm_struct *va = kasan_find_vm_area(addr); - - if (va) { - pr_err("The buggy address belongs to the virtual mapping at\n" - " [%px, %px) created by:\n" - " %pS\n", - va->addr, va->addr + va->size, va->caller); - pr_err("\n"); - - page = vmalloc_to_page(addr); - } else { - pr_err("The buggy address %px belongs to a vmalloc virtual mapping\n", addr); - } + pr_err("The buggy address %px belongs to a vmalloc virtual mapping\n", addr); + page = vmalloc_to_page(addr); }

if (page) {