CVE-2026-98524rds: ib: Clear the sg list when mapping an MR fails

Official description

In the Linux kernel, the following vulnerability has been resolved: rds: ib: Clear the sg list when mapping an MR fails rds_ib_map_frmr() stores the caller's scatterlist in the MR before DMA mapping and registration can fail. On failure, __rds_rdma_map() unpins the pages and frees the scatterlist, but rds_ib_free_frmr() can still return the MR to the pool with the stale pointer set. This leaves the pool with a dangling scatterlist and can lead to local privilege escalation. KASAN detects the resulting use-after-free when the MR is later torn down: BUG: KASAN: slab-use-after-free in __rds_ib_teardown_mr Read of size 8 Call Trace: __rds_ib_teardown_mr rds_ib_unreg_frmr rds_ib_flush_mr_pool rds_ib_flush_mrs rds_free_mr rds_setsockopt Store the scatterlist in the MR only after DMA mapping succeeds. If DMA mapping fails, return directly while the MR fields remain clear; the caller keeps ownership of the scatterlist and its pinned pages. If a later registration step fails, unmap the scatterlist and clear the MR fields before returning.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/1be3211e6ac77adbb1eac01314d989d243b32c59
• https://git.kernel.org/stable/c/c42d316163f89cd23de2f3e24558177a8c29bad8
• https://git.kernel.org/stable/c/8dca3c81344532a7f05edb3d12f31f3009410a90
• https://git.kernel.org/stable/c/49ba5ed0129906e0362c2e4b5e21c89b2a41e115
• https://git.kernel.org/stable/c/4468df5bcdef959fd96494e9968f323561a45f4c
• https://git.kernel.org/stable/c/e2ee0616260080376123997488b5cf8a3870b8d9
• https://git.kernel.org/stable/c/b36d32f30c3f1e58e3a5ae79d0f52836a316b36e
• https://git.kernel.org/stable/c/58eb1b3325edac42dc6df72c80962bd53a3c8ca7