oss-sec mailing list archives
Re: Stack-based buffer overflow in musl libc 0.8.7 and earlier
From: Kurt Seifried <kseifried () redhat com>
Date: Wed, 18 Apr 2012 11:06:42 -0600
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 04/18/2012 12:32 AM, Rich Felker wrote:
Name: Stack-based buffer overflow in musl libc 0.8.7 and earlier Software: musl 0.8.7 and earlier Software link: http://www.etalabs.net/musl Vulnerability Type: Buffer overflow Severity: Critical Software Description: musl is an implementation of the C/POSIX standard library for Linux-based systems. musl aims to be lightweight, fast, simple, free, and correct in the sense of standards-conformance and safety, and to meet requirements ranging from embedded systems and initrd images to desktop workstations, mobile devices, and high-load servers. Several build-from-source mini-distributions use musl as their C library. Vulnerability Details: musl's implementation of [v]fprintf swaps in a temporary FILE buffer on the stack when writing to unbuffered streams such as stderr. Under certain conditions where the buffer end pointer has already been set to the address of the internal degenerate buffer prior to the call to [v]fprintf, stdio internals can fail to bound access to the temporary buffer. Large writes will then overflow the temporary buffer and clobber stack contents, including potentially the return address. Any program linked to musl which includes potentially-large data from untrusted sources in its output to stderr or other unbuffered streams is affected. Solution: The vulnerability has been fixed in git, and the fix is to be included in the upcoming 0.8.8 release. A patch which applies cleanly to all recent releases is available on the musl mailing list: http://www.openwall.com/lists/musl/2012/04/17/1 Credits: This vulnerability was discovered and fixed by the author (myself, Rich Felker) while debugging a crash occurring in test code written for musl by Luka Marčetić as part of GSoC 2011.
Please use CVE-2012-2114 for this issue. - -- Kurt Seifried Red Hat Security Response Team (SRT) PGP: 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQIcBAEBAgAGBQJPjvSiAAoJEBYNRVNeJnmTzoEP/2S9w9zMzK7ILiSklpqgOqg3 SRA3UfRYYeGrpRzCfVE/Sa/u4Jg/Cjh4a5qIFOu/wgcOrOWuAjiW4eybR9zlSlyt TBrLiKN+e197ADrRX8JWJjY3LrgASlmlYZWiUkqCrNcO9QeDg2fWvFFY7HOXnbD+ tpdgTIMakAeON7HIQRvykUzxNYQhsiCZvosE4Bu6y1de7xavsqEW+FwV7OL/BjTN cSZKkp6A9M+hRRuaq07lSmOnYs5QTlb3PG8ObAo7dFWJzQLniAmKE4JIrtp7L93r eii0e6SB3uINb4RL3Q/aDEmjNzx1mRtNexUWqjPtftTZ/0mzOADMeOHcJvfio9B6 fF3eKhBmPT0BhZUx/kI3Hc6hjo0MHZQw10p2iwpThkHzpFaMxVsts0CwnoI/r+Na jwnetYl04GvJnrwVzN+Ag4x+CeOhF/jw3zECHsJ4kJ1abacJFKXBJPgxFcAvqxiY U8oDX5hneNlM5hSXNEd0fVzINVgt1mamCwu/6nEsxBp6ydIua9PBZ+ZxdnRo2U/w ZdIQKMIc27dPjlCz0D8DgSsUx1dZvVRBTsLOGlSEFuATnvoUGK4vbzdlhtnoXEQ4 QAKXQumNpj4J9wYlHirWArrs2g9sF5Aub7d2fGwMnG00b95Wpt+8/qmsrJxzti/5 L8f0eePww7O8bW2Sz7Xx =Zkg2 -----END PGP SIGNATURE-----
Current thread:
- Stack-based buffer overflow in musl libc 0.8.7 and earlier Rich Felker (Apr 18)
- Re: Stack-based buffer overflow in musl libc 0.8.7 and earlier Kurt Seifried (Apr 18)