CVE-2021-47497

Name of the Vulnerable Software and Affected Versions Linux kernel versions prior to 5.15.0-rc3+

Description The issue arises when a cell has 'nbits' equal to a multiple of BITS PER BYTE. The logic *p &= GENMASK((cell->nbits%BITS PER BYTE) - 1, 0) becomes undefined behavior because nbits modulo BITS PER BYTE is 0, and subtracting one from that results in a large number that is then shifted more than the number of bits that fit into an unsigned long. UBSAN reports this problem as a shift-out-of-bounds in drivers/nvmem/core.c.

Recommendations To resolve the issue, update the Linux kernel to a version that includes the fix for the shift-out-of-bound vulnerability. For Linux kernel versions prior to 5.15.0-rc3+, consider applying the patch that fixes the shift-out-of-bound issue in the nvmem subsystem. As a temporary workaround, consider disabling the nvmem cell read function until a patch is available.