Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: net: bridge: use a stable FDB dst snapshot in RCU readers Local FDB entries can be rewritten in place by `fdb_delete_local()`, which updates `f->dst` to another port or to `NULL` while keeping the entry alive. Several bridge RCU readers inspect `f->dst`, including `br_fdb_fillbuf()` through the `brforward_read()` sysfs path. These readers currently load `f->dst` multiple times and can therefore observe inconsistent values across the check and later dereference. In `br_fdb_fillbuf()`, this means a concurrent local-FDB update can change `f->dst` after the NULL check and before the `port_no` dereference, leading to a NULL-ptr-deref. Fix this by taking a single `READ_ONCE()` snapshot of `f->dst` in each affected RCU reader and using that snapshot for the rest of the access sequence. Also publish the in-place `f->dst` updates in `fdb_delete_local()` with `WRITE_ONCE()` so the readers and writer use matching access patterns.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 960b589f86c74ce582922fcb996103271081f4de before c502fa9f094cb03d1d1685c71e2105ab359bc2b8; affected 960b589f86c74ce582922fcb996103271081f4de before a6ae4511c07b91f597e461406c6330f0d4ff810e; affected 960b589f86c74ce582922fcb996103271081f4de before 1406c4e0ed1eaf8a29801ab1163d00fb7ee4359a; affected 960b589f86c74ce582922fcb996103271081f4de before 0b9e4bbfb7c949151e3acd44ed4aa33614d2e110; affected 960b589f86c74ce582922fcb996103271081f4de before 81af4137a30c4c2dc694dea8cacb180bd66000ef; affected 960b589f86c74ce582922fcb996103271081f4de before 5424e678f9b304e148cf5dcc047cffc7a56a3bb5; affected 960b589f86c74ce582922fcb996103271081f4de before 9a2d9d4e657b23dc21f24cf139e3aeff0b61341f; affected 960b589f86c74ce582922fcb996103271081f4de before df4601653201de21b487c3e7fffd464790cab808 |
| Linux / Linux | affected 3.14; unaffected 0 before 3.14; unaffected 5.10.259 through 5.10.*; unaffected 5.15.210 through 5.15.*; unaffected 6.1.176 through 6.1.*; unaffected 6.6.140 through 6.6.*; unaffected 6.12.86 through 6.12.*; unaffected 6.18.27 through 6.18.*; unaffected 7.0.4 through 7.0.*; unaffected 7.1 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/c502fa9f094cb03d1d1685c71e2105ab359bc2b8
- https://git.kernel.org/stable/c/a6ae4511c07b91f597e461406c6330f0d4ff810e
- https://git.kernel.org/stable/c/1406c4e0ed1eaf8a29801ab1163d00fb7ee4359a
- https://git.kernel.org/stable/c/0b9e4bbfb7c949151e3acd44ed4aa33614d2e110
- https://git.kernel.org/stable/c/81af4137a30c4c2dc694dea8cacb180bd66000ef
- https://git.kernel.org/stable/c/5424e678f9b304e148cf5dcc047cffc7a56a3bb5
- https://git.kernel.org/stable/c/9a2d9d4e657b23dc21f24cf139e3aeff0b61341f
- https://git.kernel.org/stable/c/df4601653201de21b487c3e7fffd464790cab808
ADP enrichment
No English description supplied.