[openssh-commits] [openssh] 01/02: Return ERANGE from getcwd() if buffer size is 1.

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dtucker pushed a commit to branch master
in repository openssh.

commit 527cb43fa1b4e55df661feabbac51b8e608b6519
Author: Darren Tucker <dtucker at dtucker.net>
Date:   Thu Jul 14 11:22:08 2022 +1000

    Return ERANGE from getcwd() if buffer size is 1.
    
    If getcwd() is supplied a buffer size of exactly 1 and a path of "/", it
    could result in a nul byte being written out of array bounds.  POSIX says
    it should return ERANGE if the path will not fit in the available buffer
    (with terminating nul). 1 byte cannot fit any possible path with its nul,
    so immediately return ERANGE in that case.
    
    OpenSSH never uses getcwd() with this buffer size, and all current
    (and even quite old) platforms that we are currently known to work
    on have a native getcwd() so this code is not used on those anyway.
    Reported by Qualys, ok djm@
---
 openbsd-compat/getcwd.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/openbsd-compat/getcwd.c b/openbsd-compat/getcwd.c
index 2d56bae1..a904291a 100644
--- a/openbsd-compat/getcwd.c
+++ b/openbsd-compat/getcwd.c
@@ -70,9 +70,12 @@ getcwd(char *pt, size_t size)
 	 */
 	if (pt) {
 		ptsize = 0;
-		if (!size) {
+		if (size == 0) {
 			errno = EINVAL;
 			return (NULL);
+		} else if (size == 1) {
+			errno = ERANGE;
+			return (NULL);
 		}
 		ept = pt + size;
 	} else {

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