CVE-2024-46789

In the Linux kernel, the following vulnerability has been resolved:

mm/slub: add check for s->flags in the alloctaggingslabfreehook

When enable CONFIGMEMCG & CONFIGKFENCE & CONFIGKMEMLEAK, the following warning always occurs,This is because the following call stack occurred: mempoolalloc kmemcacheallocnoprof slaballocnode kfence_alloc

Once the kfence allocation is successful,slab->objexts will not be empty, because it has already been assigned a value in kfenceinit_pool.

Since in the prepareslabobjextshook function,we perform a check for s->flags & (SLABNOOBJEXT | SLABNOLEAKTRACE),the alloctagadd function will not be called as a result.Therefore,ref->ct remains NULL.

However,when we call mempoolfree,since objext is not empty, it eventually leads to the alloctag_sub scenario being invoked. This is where the warning occurs.

So we should add corresponding checks in the alloctaggingslabfreehook. For _GFPNOOBJEXT case,I didn't see the specific case where it's using kfence,so I won't add the corresponding check in alloctaggingslabfreehook for now.

[ 3.734349] ------------[ cut here ]------------ [ 3.734807] alloctag was not set [ 3.735129] WARNING: CPU: 4 PID: 40 at ./include/linux/alloctag.h:130 kmemcachefree+0x444/0x574 [ 3.735866] Modules linked in: autofs4 [ 3.736211] CPU: 4 UID: 0 PID: 40 Comm: ksoftirqd/4 Tainted: G W 6.11.0-rc3-dirty #1 [ 3.736969] Tainted: [W]=WARN [ 3.737258] Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022 [ 3.737875] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 3.738501] pc : kmemcachefree+0x444/0x574 [ 3.738951] lr : kmemcachefree+0x444/0x574 [ 3.739361] sp : ffff80008357bb60 [ 3.739693] x29: ffff80008357bb70 x28: 0000000000000000 x27: 0000000000000000 [ 3.740338] x26: ffff80008207f000 x25: ffff000b2eb2fd60 x24: ffff0000c0005700 [ 3.740982] x23: ffff8000804229e4 x22: ffff800082080000 x21: ffff800081756000 [ 3.741630] x20: fffffd7ff8253360 x19: 00000000000000a8 x18: ffffffffffffffff [ 3.742274] x17: ffff800ab327f000 x16: ffff800083398000 x15: ffff800081756df0 [ 3.742919] x14: 0000000000000000 x13: 205d344320202020 x12: 5b5d373038343337 [ 3.743560] x11: ffff80008357b650 x10: 000000000000005d x9 : 00000000ffffffd0 [ 3.744231] x8 : 7f7f7f7f7f7f7f7f x7 : ffff80008237bad0 x6 : c0000000ffff7fff [ 3.744907] x5 : ffff80008237ba78 x4 : ffff8000820bbad0 x3 : 0000000000000001 [ 3.745580] x2 : 68d66547c09f7800 x1 : 68d66547c09f7800 x0 : 0000000000000000 [ 3.746255] Call trace: [ 3.746530] kmemcachefree+0x444/0x574 [ 3.746931] mempoolfree+0x44/0xf4 [ 3.747306] freeobjectrcu+0xc8/0xdc [ 3.747693] rcudobatch+0x234/0x8a4 [ 3.748075] rcucore+0x230/0x3e4 [ 3.748424] rcucoresi+0x14/0x1c [ 3.748780] handlesoftirqs+0x134/0x378 [ 3.749189] runksoftirqd+0x70/0x9c [ 3.749560] smpbootthreadfn+0x148/0x22c [ 3.749978] kthread+0x10c/0x118 [ 3.750323] retfrom_fork+0x10/0x20 [ 3.750696] ---[ end trace 0000000000000000 ]---