Vulnerability CVE-2021-47541
Published: 2024-05-24

Description:
In the Linux kernel, the following vulnerability has been resolved:

net/mlx4_en: Fix an use-after-free bug in mlx4_en_try_alloc_resources()

In mlx4_en_try_alloc_resources(), mlx4_en_copy_priv() is called and
tmp->tx_cq will be freed on the error path of mlx4_en_copy_priv().
After that mlx4_en_alloc_resources() is called and there is a dereference
of &tmp->tx_cq[t][i] in mlx4_en_alloc_resources(), which could lead to
a use after free problem on failure of mlx4_en_copy_priv().

Fix this bug by adding a check of mlx4_en_copy_priv()

This bug was found by a static analyzer. The analysis employs
differential checking to identify inconsistent security operations
(e.g., checks or kfrees) between two code paths and confirms that the
inconsistent operations are not recovered in the current function or
the callers, so they constitute bugs.

Note that, as a bug found by static analysis, it can be a false
positive or hard to trigger. Multiple researchers have cross-reviewed
the bug.

Builds with CONFIG_MLX4_EN=m show no new warnings,
and our static analyzer no longer warns about this code.

 References:
https://git.kernel.org/stable/c/be12572c5ddc8ad7453bada4eec8fa46967dc757
https://git.kernel.org/stable/c/676dc7d9b15bf8733233a2db1ec3f9091ab34275
https://git.kernel.org/stable/c/e461a9816a1ac5b4aeb61621b817225b61e46a68
https://git.kernel.org/stable/c/f1d43efa59f1edd3e7eca0e94559b4c6b1cd4e2b
https://git.kernel.org/stable/c/75917372eef0dbfb290ae45474314d35f97aea18
https://git.kernel.org/stable/c/addad7643142f500080417dd7272f49b7a185570
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