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| author | Dmitry V. Levin <ldv@altlinux.org> | 2018-01-07 02:03:41 +0000 |
|---|---|---|
| committer | Dmitry V. Levin <ldv@altlinux.org> | 2018-01-12 14:49:49 +0000 |
| commit | 52a713fdd0a30e1bd79818e2e3c4ab44ddca1a94 (patch) | |
| tree | 54015de9e9109423e62967df2f6b0eb2b9a4284c /sysdeps | |
| parent | 249a5895f120b13290a372a49bb4b499e749806f (diff) | |
| download | glibc-52a713fdd0a30e1bd79818e2e3c4ab44ddca1a94.zip glibc-52a713fdd0a30e1bd79818e2e3c4ab44ddca1a94.tar.gz glibc-52a713fdd0a30e1bd79818e2e3c4ab44ddca1a94.tar.bz2 | |
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.
Diffstat (limited to 'sysdeps')
| -rw-r--r-- | sysdeps/unix/sysv/linux/getcwd.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/sysdeps/unix/sysv/linux/getcwd.c b/sysdeps/unix/sysv/linux/getcwd.c index f545106..866b9d2 100644 --- a/sysdeps/unix/sysv/linux/getcwd.c +++ b/sysdeps/unix/sysv/linux/getcwd.c @@ -76,7 +76,7 @@ __getcwd (char *buf, size_t size) int retval; retval = INLINE_SYSCALL (getcwd, 2, path, alloc_size); - if (retval >= 0) + if (retval > 0 && path[0] == '/') { #ifndef NO_ALLOCATION if (buf == NULL && size == 0) @@ -92,10 +92,10 @@ __getcwd (char *buf, size_t size) return buf; } - /* The system call cannot handle paths longer than a page. - Neither can the magic symlink in /proc/self. Just use the + /* The system call either cannot handle paths longer than a page + or can succeed without returning an absolute path. Just use the generic implementation right away. */ - if (errno == ENAMETOOLONG) + if (retval >= 0 || errno == ENAMETOOLONG) { #ifndef NO_ALLOCATION if (buf == NULL && size == 0) |