Description
pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.1, src/conf.c allocates heap memory proportional to n_devices, a count derived from libxml2 XPath evaluation of the config file, without first enforcing an upper bound. On 32-bit targets (armv7l, i686 -- both listed in the project Makefile), the multiplication n_devices * sizeof(t_pusb_device) wraps around size_t, causing xmalloc() to receive a very small size. Because xmalloc() only calls abort() on NULL return, a small-but-non-NULL allocation is accepted, and subsequent array writes overflow the heap. This vulnerability is fixed in 0.9.1.
Problem types
CWE-122: Heap-based Buffer Overflow
CWE-190: Integer Overflow or Wraparound
Product status
References
github.com/...am_usb/security/advisories/GHSA-24mw-m2vf-36vp
github.com/mcdope/pam_usb/issues/352
github.com/mcdope/pam_usb/issues/55