|author||Rich Felker <firstname.lastname@example.org>||2016-04-26 15:26:40 -0400|
|committer||Rich Felker <email@example.com>||2016-04-26 15:26:40 -0400|
fix FILE buffer underflow in ungetwc
commit 7e816a6487932cbb3cb71d94b609e50e81f4e5bf (version 1.1.11 release cycle) moved the code that performs wchar_t to multibyte conversion across code that used the resulting length in bytes, thereby breaking the unget buffer space check in ungetwc and clobbering up to three bytes below the start of the buffer. for allocated FILEs (all read-enabled FILEs except stdin), the underflow clobbers at most the FILE-specific locale pointer. no stores are performed through this pointer, but subsequent loads may result in a crash or mismatching encoding rule (UTF-8 multibyte vs byte-based). for stdin, the buffer lies in .bss and the underflow may clobber another object. in practice, for libc.so the adjacent object seems to be stderr's buffer, which is completely unused, but this could vary with linking options, or when static linking. applications which do not attempt to use more than one character of ungetwc pushback, or which do not use ungetwc, are not affected.
Diffstat (limited to 'VERSION')
0 files changed, 0 insertions, 0 deletions