Out-of-bounds Write Affecting kernel-azure package, versions <5.14.21-150500.33.72.1
Threat Intelligence
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Test your applications- Snyk IDSNYK-SLES155-KERNELAZURE-8377514
- published14 Nov 2024
- disclosed13 Nov 2024
Introduced: 13 Nov 2024
CVE-2022-48980 (opens in a new tab)How to fix?
Upgrade SLES:15.5 kernel-azure to version 5.14.21-150500.33.72.1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-azure package and not the kernel-azure package as distributed by SLES.
See How to fix? for SLES:15.5 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
net: dsa: sja1105: avoid out of bounds access in sja1105_init_l2_policing()
The SJA1105 family has 45 L2 policing table entries (SJA1105_MAX_L2_POLICING_COUNT) and SJA1110 has 110 (SJA1110_MAX_L2_POLICING_COUNT). Keeping the table structure but accounting for the difference in port count (5 in SJA1105 vs 10 in SJA1110) does not fully explain the difference. Rather, the SJA1110 also has L2 ingress policers for multicast traffic. If a packet is classified as multicast, it will be processed by the policer index 99 + SRCPORT.
The sja1105_init_l2_policing() function initializes all L2 policers such that they don't interfere with normal packet reception by default. To have a common code between SJA1105 and SJA1110, the index of the multicast policer for the port is calculated because it's an index that is out of bounds for SJA1105 but in bounds for SJA1110, and a bounds check is performed.
The code fails to do the proper thing when determining what to do with the multicast policer of port 0 on SJA1105 (ds->num_ports = 5). The "mcast" index will be equal to 45, which is also equal to table->ops->max_entry_count (SJA1105_MAX_L2_POLICING_COUNT). So it passes through the check. But at the same time, SJA1105 doesn't have multicast policers. So the code programs the SHARINDX field of an out-of-bounds element in the L2 Policing table of the static config.
The comparison between index 45 and 45 entries should have determined the code to not access this policer index on SJA1105, since its memory wasn't even allocated.
With enough bad luck, the out-of-bounds write could even overwrite other valid kernel data, but in this case, the issue was detected using KASAN.
Kernel log:
sja1105 spi5.0: Probed switch chip: SJA1105Q
BUG: KASAN: slab-out-of-bounds in sja1105_setup+0x1cbc/0x2340 Write of size 8 at addr ffffff880bd57708 by task kworker/u8:0/8 ... Workqueue: events_unbound deferred_probe_work_func Call trace: ... sja1105_setup+0x1cbc/0x2340 dsa_register_switch+0x1284/0x18d0 sja1105_probe+0x748/0x840 ... Allocated by task 8: ... sja1105_setup+0x1bcc/0x2340 dsa_register_switch+0x1284/0x18d0 sja1105_probe+0x748/0x840 ...
References
- https://www.suse.com/security/cve/CVE-2022-48980.html
- https://bugzilla.suse.com/1232233
- https://git.kernel.org/stable/c/147f3e3d84054117ae6b9bf317ec4fda9f991192
- https://git.kernel.org/stable/c/5e88c6f4aaa70c542e59e5a9d2244bcc99cd245d
- https://git.kernel.org/stable/c/f8bac7f9fdb0017b32157957ffffd490f95faa07