In the Linux kernel, the following vulnerability has been resolved:
net/mlx4en: Fix an use-after-free bug in mlx4entryalloc_resources()
In mlx4entryallocresources(), mlx4encopypriv() is called and tmp->txcq will be freed on the error path of mlx4encopypriv(). After that mlx4enallocresources() is called and there is a dereference of &tmp->txcq[t][i] in mlx4enallocresources(), which could lead to a use after free problem on failure of mlx4encopy_priv().
Fix this bug by adding a check of mlx4encopy_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 CONFIGMLX4EN=m show no new warnings, and our static analyzer no longer warns about this code.