From f7a79879c0b2bef0dadd6caaaeeb0d26423e04e5 Mon Sep 17 00:00:00 2001 From: Siddhesh Poyarekar Date: Thu, 13 Jan 2022 11:28:36 +0530 Subject: realpath: Set errno to ENAMETOOLONG for result larger than PATH_MAX [BZ #28770] realpath returns an allocated string when the result exceeds PATH_MAX, which is unexpected when its second argument is not NULL. This results in the second argument (resolved) being uninitialized and also results in a memory leak since the caller expects resolved to be the same as the returned value. Return NULL and set errno to ENAMETOOLONG if the result exceeds PATH_MAX. This fixes [BZ #28770], which is CVE-2021-3998. Reviewed-by: Adhemerval Zanella Signed-off-by: Siddhesh Poyarekar (cherry picked from commit ee8d5e33adb284601c00c94687bc907e10aec9bb) --- stdlib/canonicalize.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'stdlib/canonicalize.c') diff --git a/stdlib/canonicalize.c b/stdlib/canonicalize.c index 698f9ede25..7a23a51b3a 100644 --- a/stdlib/canonicalize.c +++ b/stdlib/canonicalize.c @@ -400,8 +400,16 @@ realpath_stk (const char *name, char *resolved, error: *dest++ = '\0'; - if (resolved != NULL && dest - rname <= get_path_max ()) - rname = strcpy (resolved, rname); + if (resolved != NULL) + { + if (dest - rname <= get_path_max ()) + rname = strcpy (resolved, rname); + else + { + failed = true; + __set_errno (ENAMETOOLONG); + } + } error_nomem: scratch_buffer_free (&extra_buffer); -- cgit v1.2.3