6.6-stable review patch. If anyone has any objections, please let me know.
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From: Marco Elver elver@google.com
commit 6ade153349c6bb990d170cecc3e8bdd8628119ab upstream.
Since 6ee9b3d84775 ("kasan: remove kasan_find_vm_area() to prevent possible deadlock"), more detailed info about the vmalloc mapping and the origin was dropped due to potential deadlocks.
While fixing the deadlock is necessary, that patch was too quick in killing an otherwise useful feature, and did no due-diligence in understanding if an alternative option is available.
Restore printing more helpful vmalloc allocation info in KASAN reports with the help of vmalloc_dump_obj(). Example report:
| BUG: KASAN: vmalloc-out-of-bounds in vmalloc_oob+0x4c9/0x610 | Read of size 1 at addr ffffc900002fd7f3 by task kunit_try_catch/493 | | CPU: [...] | Call Trace: | <TASK> | dump_stack_lvl+0xa8/0xf0 | print_report+0x17e/0x810 | kasan_report+0x155/0x190 | vmalloc_oob+0x4c9/0x610 | [...] | | The buggy address belongs to a 1-page vmalloc region starting at 0xffffc900002fd000 allocated at vmalloc_oob+0x36/0x610 | The buggy address belongs to the physical page: | page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x126364 | flags: 0x200000000000000(node=0|zone=2) | raw: 0200000000000000 0000000000000000 dead000000000122 0000000000000000 | raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000 | page dumped because: kasan: bad access detected | | [..]
Link: https://lkml.kernel.org/r/20250716152448.3877201-1-elver@google.com Fixes: 6ee9b3d84775 ("kasan: remove kasan_find_vm_area() to prevent possible deadlock") Signed-off-by: Marco Elver elver@google.com Suggested-by: Uladzislau Rezki urezki@gmail.com Acked-by: Uladzislau Rezki (Sony) urezki@gmail.com Cc: Alexander Potapenko glider@google.com Cc: Andrey Konovalov andreyknvl@gmail.com Cc: Andrey Ryabinin ryabinin.a.a@gmail.com Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Cc: Yeoreum Yun yeoreum.yun@arm.com Cc: Yunseong Kim ysk@kzalloc.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/kasan/report.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -385,7 +385,9 @@ static void print_address_description(vo }
if (is_vmalloc_addr(addr)) { - pr_err("The buggy address %px belongs to a vmalloc virtual mapping\n", addr); + pr_err("The buggy address belongs to a"); + if (!vmalloc_dump_obj(addr)) + pr_cont(" vmalloc virtual mapping\n"); page = vmalloc_to_page(addr); }