Affected: Linux, linux_kernel

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 kthrea…