A stack-based buffer overflow was found in libresolv when invoked from nssdns, allowing specially crafted DNS responses to seize control of EIP in the DNS client.

The buffer overflow occurs in the functions senddg (send datagram) and sendvc (send TCP) for the NSS module libnssdns.so.2 when calling getaddrinfo with AFUNSPEC family, or in some cases AFINET6 family. The use of AFUNSPEC (or AFINET6 in some cases) triggers the low-level resolver code to send out two parallel queries for A and AAAA. A mismanagement of the buffers used for those queries could result in the response of a query writing beyond the alloca allocated buffer created by resnquery.

An integer overflow, leading to buffer overflow flaw was found in the way the implementation of strcoll() routine, used to compare two strings based on the current locale, of glibc, the GNU libc libraries, performed calculation of memory requirements / allocation, needed for storage of the strings. If an application linked against glibc was missing an application-level sanity checks for validity of strcoll() arguments and accepted untrusted input, an attacker could use this flaw to cause the particular application to crash or, potentially, execute arbitrary code with the privileges of the user running the application.

Upstream bug report (including reproducer): [1] http://sourceware.org/bugzilla/showbug.cgi?id=14547

ld.so in the GNU C Library (aka glibc or libc6) before 2.11.3, and 2.12.x before 2.12.2, does not properly restrict use of the LDAUDIT environment variable to reference dynamic shared objects (DSOs) as audit objects, which allows local users to gain privileges by leveraging an unsafe DSO located in a trusted library directory, as demonstrated by libpcprofile.so.

elf/dl-load.c in ld.so in the GNU C Library (aka glibc or libc6) through 2.11.2, and 2.12.x through 2.12.1, does not properly handle a value of $ORIGIN for the LDAUDIT environment variable, which allows local users to gain privileges via a crafted dynamic shared object (DSO) located in an arbitrary directory.

A security flaw was found in the way strcoll() interface of glibc, the GNU libc libraries, performed failsafe back to alloca() routine when malloc() function call failed previously (due to out of memory [OOM] condition for example). If an application linked against glibc was missing an application-level sanity checks for validity of strcoll() arguments and accepted untrusted input, an attacker could use this flaw to cause the particular application to crash or, potentially, execute arbitrary code with the privileges of the user running the application.

Upstream bug report (including the reproducer): [1] http://sourceware.org/bugzilla/showbug.cgi?id=14552#c0

Issue / part: 1) alloca() stack overflow from [1].

References: [2] http://www.openwall.com/lists/oss-security/2012/09/07/9 [3] http://www.openwall.com/lists/oss-security/2012/09/07/15 [4] http://www.openwall.com/lists/oss-security/2012/09/10/1 [5] http://www.openwall.com/lists/oss-security/2012/09/10/3 [6] http://www.openwall.com/lists/oss-security/2012/09/13/16

Stack consumption vulnerability in the regcomp implementation in the GNU C Library (aka glibc or libc6) through 2.11.3, and 2.12.x through 2.12.2, allows context-dependent attackers to cause a denial of service (resource exhaustion) via a regular expression containing adjacent repetition operators, as demonstrated by a {10,}{10,}{10,}{10,} sequence in the proftpd.gnu.c exploit for ProFTPD.

Maksymilian Arciemowicz reported a deficiency in the way glibc regular expression engine processed certain patterns. A local attacker could use this flaw to cause a denial of service (crash due stack overflow).

Note: The above described behavior is a limitation of glibc regular expression engine. Regular expression matching function is called recursively for certain types of patterns (where subexpression using quantifier is nested inside of another quantified expression), where long input can result in deep recursion and exhaustion of all stack memory (i.e. impact is limited to crash). Amount of stack memory available to glibc regular expression engine influences the size of input that must be provided to trigger the crash. Alternatively, expression can be modified to avoid quantification nesting, or program modified to limit size of input passed to regular expression engine.

Conclusion: Due the above described behavior Red Hat Security Response Team would not classify this deficiency to be a security issue.

References: [1] http://www.kb.cert.org/vuls/id/912279 [2] http://www.securityfocus.com/archive/1/515589 [3] http://forums.cnet.com/7726-6132102-5042238.html [4] http://secunia.com/advisories/42547/ [5] http://securityreason.com/securityalert/8003