From: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Subject: kasan, mm: perform untagged pointers comparison in krealloc The krealloc function checks where the same buffer was reused or a new one allocated by comparing kernel pointers. Tag-based KASAN changes memory tag on the krealloc'ed chunk of memory and therefore also changes the pointer tag of the returned pointer. Therefore we need to perform comparison on untagged (with tags reset) pointers to check whether it's the same memory region or not. Link: http://lkml.kernel.org/r/14f6190d7846186a3506cd66d82446646fe65090.1544099024.git.andreyknvl@xxxxxxxxxx Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Reviewed-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- --- a/mm/slab_common.c~kasan-mm-perform-untagged-pointers-comparison-in-krealloc +++ a/mm/slab_common.c @@ -1534,7 +1534,7 @@ void *krealloc(const void *p, size_t new } ret = __do_krealloc(p, new_size, flags); - if (ret && p != ret) + if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret)) kfree(p); return ret; _
