{"id":"CVE-2026-23438","title":"net: mvpp2: guard flow control update with global_tx_fc in buffer switching","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: mvpp2: guard flow control update with global_tx_fc in buffer switching\n\nmvpp2_bm_switch_buffers() unconditionally calls\nmvpp2_bm_pool_update_priv_fc() when switchi…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < 0cfcd31f98fc608dc9406bff3fee3a9dd364d014","Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < da089f74a993f846685067b14158cb41b879ff29","Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < ff0c54f088f7ab91dbbf47cf8244460f99122750","Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < 7bd20f4b3ef3044dc55acd5b8ef748a70d29d03f","Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < 7df2b50cae1a76cbb90b294f3edb61e3e10bf2e9","Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < 8baced53a35fc9710f80d6ca016a2c418dc3231f","Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < 8a63baadf08453f66eb582fdb6dd234f72024723","Linux 5.12"],"published":"2026-04-03","updated":"2026-09-08","sourceUpdated":"2026-09-08T08:46:11.063Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-23438","references":[{"url":"https://git.kernel.org/stable/c/0cfcd31f98fc608dc9406bff3fee3a9dd364d014"},{"url":"https://git.kernel.org/stable/c/da089f74a993f846685067b14158cb41b879ff29"},{"url":"https://git.kernel.org/stable/c/ff0c54f088f7ab91dbbf47cf8244460f99122750"},{"url":"https://git.kernel.org/stable/c/7bd20f4b3ef3044dc55acd5b8ef748a70d29d03f"},{"url":"https://git.kernel.org/stable/c/7df2b50cae1a76cbb90b294f3edb61e3e10bf2e9"},{"url":"https://git.kernel.org/stable/c/8baced53a35fc9710f80d6ca016a2c418dc3231f"},{"url":"https://git.kernel.org/stable/c/8a63baadf08453f66eb582fdb6dd234f72024723"}],"tags":["cve.org"],"epss":0.00125,"epssPercentile":0.01892,"ingestedAt":"2026-09-08T15:33:26.992Z","slug":"CVE-2026-23438","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet: mvpp2: guard flow control update with global_tx_fc in buffer switching\n\nmvpp2_bm_switch_buffers() unconditionally calls\nmvpp2_bm_pool_update_priv_fc() when switching between per-cpu and\nshared buffer pool modes. This function programs CM3 flow control\nregisters via mvpp2_cm3_read()/mvpp2_cm3_write(), which dereference\npriv->cm3_base without any NULL check.\n\nWhen the CM3 SRAM resource is not present in the device tree (the\nthird reg entry added by commit 60523583b07c (\"dts: marvell: add CM3\nSRAM memory to cp11x ethernet device tree\")), priv->cm3_base remains\nNULL and priv->global_tx_fc is false. Any operation that triggers\nmvpp2_bm_switch_buffers(), for example an MTU change that crosses\nthe jumbo frame threshold, will crash:\n\n  Unable to handle kernel NULL pointer dereference at\n  virtual address 0000000000000000\n  Mem abort info:\n    ESR = 0x0000000096000006\n    EC = 0x25: DABT (current EL), IL = 32 bits\n  pc : readl+0x0/0x18\n  lr : mvpp2_cm3_read.isra.0+0x14/0x20\n  Call trace:\n   readl+0x0/0x18\n   mvpp2_bm_pool_update_fc+0x40/0x12c\n   mvpp2_bm_pool_update_priv_fc+0x94/0xd8\n   mvpp2_bm_switch_buffers.isra.0+0x80/0x1c0\n   mvpp2_change_mtu+0x140/0x380\n   __dev_set_mtu+0x1c/0x38\n   dev_set_mtu_ext+0x78/0x118\n   dev_set_mtu+0x48/0xa8\n   dev_ifsioc+0x21c/0x43c\n   dev_ioctl+0x2d8/0x42c\n   sock_ioctl+0x314/0x378\n\nEvery other flow control call site in the driver already guards\nhardware access with either priv->global_tx_fc or port->tx_fc.\nmvpp2_bm_switch_buffers() is the only place that omits this check.\n\nAdd the missing priv->global_tx_fc guard to both the disable and\nre-enable calls in mvpp2_bm_switch_buffers(), consistent with the\nrest of the driver.\n\n## Affected\n\n- `Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < 0cfcd31f98fc608dc9406bff3fee3a9dd364d014`\n- `Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < da089f74a993f846685067b14158cb41b879ff29`\n- `Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < ff0c54f088f7ab91dbbf47cf8244460f99122750`\n- `Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < 7bd20f4b3ef3044dc55acd5b8ef748a70d29d03f`\n- `Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < 7df2b50cae1a76cbb90b294f3edb61e3e10bf2e9`\n- `Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < 8baced53a35fc9710f80d6ca016a2c418dc3231f`\n- `Linux >= 3a616b92a9d17448d96a33bf58e69f01457fd43a < 8a63baadf08453f66eb582fdb6dd234f72024723`\n- `Linux 5.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}