Vulnerability CVE-2021-4441
Published: 2024-08-22

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

spi: spi-zynq-qspi: Fix a NULL pointer dereference in zynq_qspi_exec_mem_op()

In zynq_qspi_exec_mem_op(), kzalloc() is directly used in memset(),
which could lead to a NULL pointer dereference on failure of
kzalloc().

Fix this bug by adding a check of tmpbuf.

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

 References:
https://git.kernel.org/stable/c/df14d2bed8e2455878e046e67123d9ecb2e79056
https://git.kernel.org/stable/c/2efece1368aeee2d2552c7ec36aeb676c4d4c95f
https://git.kernel.org/stable/c/3c32405d6474a21f7d742828e73c13e326dcae82
https://git.kernel.org/stable/c/b9dd08cbebe0c593c49bf86d2012a431494e54cb
https://git.kernel.org/stable/c/ab3824427b848da10e9fe2727f035bbeecae6ff4
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