# CVE-2026-46110: linux: In the Linux kernel, the following vulnerability has been resolved: net: stmmac: Prevent NULL deref when RX memory e... CVE-2026-46110 is fixed in 14 products on 1 platform, first by SUSE-SU-2026:22087-1, released June 5, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-46110 - Priority: High - CVSS: 7.5 (high) - EPSS: 0.0051 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: May 28, 2026 ## Description In the Linux kernel, the following vulnerability has been resolved: net: stmmac: Prevent NULL deref when RX memory exhausted The CPU receives frames from the MAC through conventional DMA: the CPU allocates buffers for the MAC, then the MAC fills them and returns ownership to the CPU. For each hardware RX queue, the CPU and MAC coordinate through a shared ring array of DMA descriptors: one descriptor per DMA buffer. Each descriptor includes the buffer's physical address and a status flag ("OWN") indicating which side owns the buffer: OWN=0 for CPU, OWN=1 for MAC. The CPU is only allowed to set the flag and the MAC is only allowed to clear it, and both must move through the ring in sequence: thus the ring is used for both "submissions" and "completions." In the stmmac driver, stmmac_rx() bookmarks its position in the ring with the `cur_rx` index. The main receive loop in that function checks for rx_descs[cur_rx].own=0, gives the corresponding buffer to the network stack (NULLing the pointer), and increments `cur_rx` modulo the ring size. After the loop exits, stmmac_rx_refill(), which bookmarks its position with `dirty_rx`, allocates fresh buffers and rearms the descriptors (setting OWN=1). If it fails any allocation, it simply stops early (leaving OWN=0) and will retry where it left off when next called. This means descriptors have a three-stage lifecycle (terms my own): - `empty` (OWN=1, buffer valid) - `full` (OWN=0, buffer valid and populated) - `dirty` (OWN=0, buffer NULL) But because stmmac_rx() only checks OWN, it confuses `full`/`dirty`. In the past (see 'Fixes:'), there was a bug where the loop could cycle `cur_rx` all the way back to the first descriptor it dirtied, resulting in a NULL dereference when mistaken for `full`. The aforementioned commit resolved that *specific* failure by capping the loop's iteration limit at `dma_rx_size - 1`, but this is only a partial fix: if the previous stmmac_rx_refill() didn't complete, then there are leftover `dirty` descriptors that the loop might encounter without needing to cycle fully around. The current code therefore panics (see 'Closes:') when stmmac_rx_refill() is memory-starved long enough for `cur_rx` to catch up to `dirty_rx`. Fix this by explicitly checking, before advancing `cur_rx`, if the next entry is dirty; exit the loop if so. This prevents processing of the final, used descriptor until stmmac_rx_refill() succeeds, but fully prevents the `cur_rx == dirty_rx` ambiguity as the previous bugfix intended: so remove the clamp as well. Since stmmac_rx_zc() is a copy-paste-and-tweak of stmmac_rx() and the code structure is identical, any fix to stmmac_rx() will also need a corresponding fix for stmmac_rx_zc(). Therefore, apply the same check there. In stmmac_rx() (not stmmac_rx_zc()), a related bug remains: after the MAC sets OWN=0 on the final descriptor, it will be unable to send any further DMA-complete IRQs until it's given more `empty` descriptors. Currently, the driver simply *hopes* that the next stmmac_rx_refill() succeeds, risking an indefinite stall of the receive process if not. But this is not a regression, so it can be addressed in a future change. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | kernel-64kb sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-64kb sles 16.0 | 6.12.0-160000.34.1 | [SUSE-SU-2026:22087-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22087-1.md) | Jun 5, 2026 | | Linux | kernel-azure sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-azure sles 16.0 | 6.12.0-160000.34.1 | [SUSE-SU-2026:22087-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22087-1.md) | Jun 5, 2026 | | Linux | kernel-default sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-default sles 16.0 | 6.12.0-160000.34.1 | [SUSE-SU-2026:22087-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22087-1.md) | Jun 5, 2026 | | Linux | kernel-default-base sles 15.7 | 6.4.0-150700.53.60.1.150700.17.35.4 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-default-base sles 16.0 | 6.12.0-160000.34.1.160000.2.15 | [SUSE-SU-2026:22087-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22087-1.md) | Jun 5, 2026 | | Linux | kernel-docs sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-docs sles 16.0 | 6.12.0-160000.34.1 | [SUSE-SU-2026:22087-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22087-1.md) | Jun 5, 2026 | | Linux | kernel-kvmsmall sles 16.0 | 6.12.0-160000.34.1 | [SUSE-SU-2026:22087-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22087-1.md) | Jun 5, 2026 | | Linux | kernel-livepatch-SLE15-SP7-RT_Update_16 sles 15.7 | 1-150700.1.5.2 | [SUSE-SU-2026:2591-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2591-1.md) | Jun 23, 2026 | | Linux | kernel-livepatch-SLE15-SP7_Update_16 sles 15.7 | 1-150700.15.3.2 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-obs-build sles 15.7 | 6.4.0-150700.53.60.2 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-obs-qa sles 16.0 | 6.12.0-160000.34.1 | [SUSE-SU-2026:22087-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22087-1.md) | Jun 5, 2026 | | Linux | kernel-source sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-source sles 16.0 | 6.12.0-160000.34.1 | [SUSE-SU-2026:22087-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22087-1.md) | Jun 5, 2026 | | Linux | kernel-syms sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-syms sles 16.0 | 6.12.0-160000.34.1 | [SUSE-SU-2026:22087-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22087-1.md) | Jun 5, 2026 | | Linux | kernel-zfcpdump sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-zfcpdump sles 16.0 | 6.12.0-160000.34.1 | [SUSE-SU-2026:22087-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22087-1.md) | Jun 5, 2026 | | Linux | linux Debian 12.15 (bookworm) | 6.1.176-1 | [DEBIAN-CVE-2026-46110](https://patchblox.com/security/data/fix/linux/debian-cve-2026-46110.md) | Jun 24, 2026 | | Linux | linux Debian 13.5 (trixie) | 6.12.88-1 | [DEBIAN-CVE-2026-46110](https://patchblox.com/security/data/fix/linux/debian-cve-2026-46110.md) | Jun 24, 2026 | | Linux | linux Debian 14 | 7.0.7-1 | [DEBIAN-CVE-2026-46110](https://patchblox.com/security/data/fix/linux/debian-cve-2026-46110.md) | Jun 24, 2026 | --- Data as of 2026-11-08T06:59:42Z UTC. 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