From 52a713fdd0a30e1bd79818e2e3c4ab44ddca1a94 Mon Sep 17 00:00:00 2001 From: "Dmitry V. Levin" Date: Sun, 7 Jan 2018 02:03:41 +0000 Subject: linux: make getcwd(3) fail if it cannot obtain an absolute path [BZ #22679] Currently getcwd(3) can succeed without returning an absolute path because the underlying getcwd syscall, starting with linux commit v2.6.36-rc1~96^2~2, may succeed without returning an absolute path. This is a conformance issue because "The getcwd() function shall place an absolute pathname of the current working directory in the array pointed to by buf, and return buf". This is also a security issue because a non-absolute path returned by getcwd(3) causes a buffer underflow in realpath(3). Fix this by checking the path returned by getcwd syscall and falling back to generic_getcwd if the path is not absolute, effectively making getcwd(3) fail with ENOENT. The error code is chosen for consistency with the case when the current directory is unlinked. [BZ #22679] CVE-2018-1000001 * sysdeps/unix/sysv/linux/getcwd.c (__getcwd): Fall back to generic_getcwd if the path returned by getcwd syscall is not absolute. * io/tst-getcwd-abspath.c: New test. * io/Makefile (tests): Add tst-getcwd-abspath. --- ChangeLog | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'ChangeLog') diff --git a/ChangeLog b/ChangeLog index fb280c1de5..971257a4bd 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,12 @@ +2018-01-12 Dmitry V. Levin + + [BZ #22679] + CVE-2018-1000001 + * sysdeps/unix/sysv/linux/getcwd.c (__getcwd): Fall back to + generic_getcwd if the path returned by getcwd syscall is not absolute. + * io/tst-getcwd-abspath.c: New test. + * io/Makefile (tests): Add tst-getcwd-abspath. + 2018-01-12 Istvan Kurucsai * malloc/malloc.c (malloc_consolidate): Add size check. -- cgit v1.2.3-70-g09d2