Subject: CVE-2024-35854: mlxsw: spectrum_acl_tcam: Fix possible use-after-free during rehash

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

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

mlxsw: spectrum_acl_tcam: Fix possible use-after-free during rehash

The rehash delayed work migrates filters from one region to another
according to the number of available credits.

The migrated from region is destroyed at the end of the work if the
number of credits is non-negative as the assumption is that this is
indicative of migration being complete. This assumption is incorrect as
a non-negative number of credits can also be the result of a failed
migration.

The destruction of a region that still has filters referencing it can
result in a use-after-free [1].

Fix by not destroying the region if migration failed.

[1]
BUG: KASAN: slab-use-after-free in mlxsw_sp_acl_ctcam_region_entry_remove+0x21d/0x230
Read of size 8 at addr ffff8881735319e8 by task kworker/0:31/3858

CPU: 0 PID: 3858 Comm: kworker/0:31 Tainted: G        W          6.9.0-rc2-custom-00782-gf2275c2157d8 #5
Hardware name: Mellanox Technologies Ltd. MSN3700/VMOD0005, BIOS 5.11 01/06/2019
Workqueue: mlxsw_core mlxsw_sp_acl_tcam_vregion_rehash_work
Call Trace:
 <TASK>
 dump_stack_lvl+0xc6/0x120
 print_report+0xce/0x670
 kasan_report+0xd7/0x110
 mlxsw_sp_acl_ctcam_region_entry_remove+0x21d/0x230
 mlxsw_sp_acl_ctcam_entry_del+0x2e/0x70
 mlxsw_sp_acl_atcam_entry_del+0x81/0x210
 mlxsw_sp_acl_tcam_vchunk_migrate_all+0x3cd/0xb50
 mlxsw_sp_acl_tcam_vregion_rehash_work+0x157/0x1300
 process_one_work+0x8eb/0x19b0
 worker_thread+0x6c9/0xf70
 kthread+0x2c9/0x3b0
 ret_from_fork+0x4d/0x80
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 174:
 kasan_save_stack+0x33/0x60
 kasan_save_track+0x14/0x30
 __kasan_kmalloc+0x8f/0xa0
 __kmalloc+0x19c/0x360
 mlxsw_sp_acl_tcam_region_create+0xdf/0x9c0
 mlxsw_sp_acl_tcam_vregion_rehash_work+0x954/0x1300
 process_one_work+0x8eb/0x19b0
 worker_thread+0x6c9/0xf70
 kthread+0x2c9/0x3b0
 ret_from_fork+0x4d/0x80
 ret_from_fork_asm+0x1a/0x30

Freed by task 7:
 kasan_save_stack+0x33/0x60
 kasan_save_track+0x14/0x30
 kasan_save_free_info+0x3b/0x60
 poison_slab_object+0x102/0x170
 __kasan_slab_free+0x14/0x30
 kfree+0xc1/0x290
 mlxsw_sp_acl_tcam_region_destroy+0x272/0x310
 mlxsw_sp_acl_tcam_vregion_rehash_work+0x731/0x1300
 process_one_work+0x8eb/0x19b0
 worker_thread+0x6c9/0xf70
 kthread+0x2c9/0x3b0
 ret_from_fork+0x4d/0x80
 ret_from_fork_asm+0x1a/0x30

The Linux kernel CVE team has assigned CVE-2024-35854 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 5.1 with commit c9c9af91f1d9 and fixed in 5.4.275 with commit e118e7ea24d1
	Issue introduced in 5.1 with commit c9c9af91f1d9 and fixed in 5.10.216 with commit a429a912d6c7
	Issue introduced in 5.1 with commit c9c9af91f1d9 and fixed in 5.15.158 with commit 4c89642ca47f
	Issue introduced in 5.1 with commit c9c9af91f1d9 and fixed in 6.1.90 with commit 813e2ab753a8
	Issue introduced in 5.1 with commit c9c9af91f1d9 and fixed in 6.6.30 with commit 311eeaa7b9e2
	Issue introduced in 5.1 with commit c9c9af91f1d9 and fixed in 6.8.9 with commit a02687044e12
	Issue introduced in 5.1 with commit c9c9af91f1d9 and fixed in 6.9 with commit 542259888899

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-35854
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/e118e7ea24d1392878ef85926627c6bc640c4388
	https://git.kernel.org/stable/c/a429a912d6c779807f4d72a6cc0a1efaaa3613e1
	https://git.kernel.org/stable/c/4c89642ca47fb620914780c7c51d8d1248201121
	https://git.kernel.org/stable/c/813e2ab753a8f8c243a39ede20c2e0adc15f3887
	https://git.kernel.org/stable/c/311eeaa7b9e26aba5b3d57b09859f07d8e9fc049
	https://git.kernel.org/stable/c/a02687044e124f8ccb427cd3632124a4e1a7d7c1
	https://git.kernel.org/stable/c/54225988889931467a9b55fdbef534079b665519