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charset="utf-8" From: Peng Fan With "slub_debug=3DFUZ init_on_free=3D1 loglevel=3D7" set in bootargs and CONFIG_SLAB_FREELIST_HARDENED is set. There is kernel dump: [ 0.000000] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D [ 0.000000] BUG kmalloc-8 (Not tainted): kmalloc Redzone overwritten [ 0.000000] ------------------------------------------------------------= ----------------- [ 0.000000] [ 0.000000] 0xffff000010032858-0xffff00001003285f @offset=3D2136. First = byte 0x0 instead of 0xcc [ 0.000000] FIX kmalloc-8: Restoring kmalloc Redzone 0xffff000010032858-= 0xffff00001003285f=3D0xcc [ 0.000000] Slab 0xfffffdffc0400c80 objects=3D36 used=3D23 fp=3D0xffff00= 0010032a18 flags=3D0x3fffe0000000200(workingset|node=3D0|zone=3D0|lastcpupi= d=3D0x1ffff) [ 0.000000] Object 0xffff000010032858 @offset=3D2136 fp=3D0xffff00001003= 28c8 [ 0.000000] [ 0.000000] Redzone ffff000010032850: cc cc cc cc cc cc cc cc = ........ [ 0.000000] Object ffff000010032858: cc cc cc cc cc cc cc cc = ........ [ 0.000000] Redzone ffff000010032860: cc cc cc cc cc cc cc cc = ........ [ 0.000000] Padding ffff0000100328b4: 00 00 00 00 00 00 00 00 00 00 00 = 00 ............ [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.11.0-rc3-= next-20240814-00004-g61844c55c3f4 #144 [ 0.000000] Hardware name: NXP i.MX95 19X19 board (DT) [ 0.000000] Call trace: [ 0.000000] dump_backtrace+0x90/0xe8 [ 0.000000] show_stack+0x18/0x24 [ 0.000000] dump_stack_lvl+0x74/0x8c [ 0.000000] dump_stack+0x18/0x24 [ 0.000000] print_trailer+0x150/0x218 [ 0.000000] check_object+0xe4/0x454 [ 0.000000] free_to_partial_list+0x2f8/0x5ec It is because the kmalloc redzone area is cleared or orig_size is cleared. When s->object_size is larger than orig_size, just clear the orig_size area. And restore the value of orig_size. Fixes: d57a964e09c2 ("kasan, mm: integrate slab init_on_free with HW_TAGS") Signed-off-by: Peng Fan --- mm/slub.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 94f5a4143825..d03957d15bbf 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2282,14 +2282,22 @@ bool slab_free_hook(struct kmem_cache *s, void *x, = bool init, */ if (unlikely(init)) { int rsize; - unsigned int inuse; + unsigned int inuse, orig_size; =20 inuse =3D get_info_end(s); + orig_size =3D get_orig_size(s, x); if (!kasan_has_integrated_init()) - memset(kasan_reset_tag(x), 0, s->object_size); + memset(kasan_reset_tag(x), 0, + s->object_size > orig_size ? orig_size : s->object_size); rsize =3D (s->flags & SLAB_RED_ZONE) ? s->red_left_pad : 0; memset((char *)kasan_reset_tag(x) + inuse, 0, s->size - inuse - rsize); + /* + * Restore orig_size, otherwize kmalloc redzone overwritten + * would be reported + */ + set_orig_size(s, x, orig_size); + } /* KASAN might put x into memory quarantine, delaying its reuse. */ return !kasan_slab_free(s, x, init, still_accessible); --=20 2.37.1