From 8f5e8b01a1da2a207228f2072c934fa5918554b8 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Fri, 4 Dec 2015 20:36:28 +0000 Subject: Fix nan functions handling of payload strings (bug 16961, bug 16962). The nan, nanf and nanl functions handle payload strings by doing e.g.: if (tagp[0] != '\0') { char buf[6 + strlen (tagp)]; sprintf (buf, "NAN(%s)", tagp); return strtod (buf, NULL); } This is an unbounded stack allocation based on the length of the argument. Furthermore, if the argument starts with an n-char-sequence followed by ')', that n-char-sequence is wrongly treated as significant for determining the payload of the resulting NaN, when ISO C says the call should be equivalent to strtod ("NAN", NULL), without being affected by that initial n-char-sequence. This patch fixes both those problems by using the __strtod_nan etc. functions recently factored out of strtod etc. for that purpose, with those functions being exported from libc at version GLIBC_PRIVATE. Tested for x86_64, x86, mips64 and powerpc. [BZ #16961] [BZ #16962] * math/s_nan.c (__nan): Use __strtod_nan instead of constructing a string on the stack for strtod. * math/s_nanf.c (__nanf): Use __strtof_nan instead of constructing a string on the stack for strtof. * math/s_nanl.c (__nanl): Use __strtold_nan instead of constructing a string on the stack for strtold. * stdlib/Versions (libc): Add __strtof_nan, __strtod_nan and __strtold_nan to GLIBC_PRIVATE. * math/test-nan-overflow.c: New file. * math/test-nan-payload.c: Likewise. * math/Makefile (tests): Add test-nan-overflow and test-nan-payload. --- NEWS | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'NEWS') diff --git a/NEWS b/NEWS index cb61a3a..37189f7 100644 --- a/NEWS +++ b/NEWS @@ -60,6 +60,12 @@ Version 2.23 C Library is GCC 4.7. Older GCC versions, and non-GNU compilers, can still be used to compile programs using the GNU C Library. +Security related changes: + +* The nan, nanf and nanl functions no longer have unbounded stack usage + depending on the length of the string passed as an argument to the + functions. Reported by Joseph Myers. + * The following bugs are resolved with this release: [The release manager will add the list generated by -- cgit v1.1