Out-of-bounds Write Affecting glibc package, versions <0:2.17-322.181.amzn1

Note: Versions mentioned in the description apply only to the upstream glibc package and not the glibc package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2018.03 relevant fixed versions and status.

sysdeps/i386/ldbl2mpn.c in the GNU C Library (aka glibc or libc6) before 2.23 on x86 targets has a stack-based buffer overflow if the input to any of the printf family of functions is an 80-bit long double with a non-canonical bit pattern, as seen when passing a \x00\x04\x00\x00\x00\x00\x00\x00\x00\x04 value to sprintf. NOTE: the issue does not affect glibc by default in 2016 or later (i.e., 2.23 or later) because of commits made in 2015 for inlining of C99 math functions through use of GCC built-ins. In other words, the reference to 2.23 is intentional despite the mention of "Fixed for glibc 2.33" in the 26649 reference.

• https://security.netapp.com/advisory/ntap-20210122-0004/
• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-29573
• https://security.gentoo.org/glsa/202101-20
• https://sourceware.org/bugzilla/show_bug.cgi?id=26649
• https://sourceware.org/pipermail/libc-alpha/2020-September/117779.html