From: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
To: libc-stable@sourceware.org
Cc: Andreas Schwab <schwab@suse.de>
Subject: [2.28 COMMITTED] Fix use-after-free in glob when expanding ~user (bug 25414)
Date: Fri, 20 Mar 2020 18:03:33 -0300 [thread overview]
Message-ID: <20200320210333.202385-2-tuliom@linux.ibm.com> (raw)
In-Reply-To: <20200320210333.202385-1-tuliom@linux.ibm.com>
From: Andreas Schwab <schwab@suse.de>
The value of `end_name' points into the value of `dirname', thus don't
deallocate the latter before the last use of the former.
(cherry picked from commit ddc650e9b3dc916eab417ce9f79e67337b05035c)
---
NEWS | 4 ++++
posix/glob.c | 25 +++++++++++++------------
2 files changed, 17 insertions(+), 12 deletions(-)
diff --git a/NEWS b/NEWS
index 038541c83b..1d00542a5d 100644
--- a/NEWS
+++ b/NEWS
@@ -73,6 +73,7 @@ The following bugs are resolved with this release:
[25204] Ignore LD_PREFER_MAP_32BIT_EXEC for SUID programs
[25225] ld.so fails to link on x86 if GCC defaults to -fcf-protection
[25232] No const correctness for strchr et al. for Clang++
+ [25414] 'glob' use-after-free bug (CVE-2020-1752)
[25423] Array overflow in backtrace on powerpc
Security related changes:
@@ -109,6 +110,9 @@ Security related changes:
addresses for loaded libraries and thus bypass ASLR for a setuid
program. Reported by Marcin Kościelnicki.
+ CVE-2020-1752: A use-after-free vulnerability in the glob function when
+ expanding ~user has been fixed.
+
\f
Version 2.28
diff --git a/posix/glob.c b/posix/glob.c
index 8444b2f79e..1b389d2da1 100644
--- a/posix/glob.c
+++ b/posix/glob.c
@@ -827,31 +827,32 @@ __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
{
size_t home_len = strlen (p->pw_dir);
size_t rest_len = end_name == NULL ? 0 : strlen (end_name);
- char *d;
+ char *d, *newp;
+ bool use_alloca = glob_use_alloca (alloca_used,
+ home_len + rest_len + 1);
- if (__glibc_unlikely (malloc_dirname))
- free (dirname);
- malloc_dirname = 0;
-
- if (glob_use_alloca (alloca_used, home_len + rest_len + 1))
- dirname = alloca_account (home_len + rest_len + 1,
- alloca_used);
+ if (use_alloca)
+ newp = alloca_account (home_len + rest_len + 1, alloca_used);
else
{
- dirname = malloc (home_len + rest_len + 1);
- if (dirname == NULL)
+ newp = malloc (home_len + rest_len + 1);
+ if (newp == NULL)
{
scratch_buffer_free (&pwtmpbuf);
retval = GLOB_NOSPACE;
goto out;
}
- malloc_dirname = 1;
}
- d = mempcpy (dirname, p->pw_dir, home_len);
+ d = mempcpy (newp, p->pw_dir, home_len);
if (end_name != NULL)
d = mempcpy (d, end_name, rest_len);
*d = '\0';
+ if (__glibc_unlikely (malloc_dirname))
+ free (dirname);
+ dirname = newp;
+ malloc_dirname = !use_alloca;
+
dirlen = home_len + rest_len;
dirname_modified = 1;
}
--
2.24.1
prev parent reply other threads:[~2020-03-20 21:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-20 21:03 [2.28 COMMITTED] Fix array overflow in backtrace on PowerPC (bug 25423) Tulio Magno Quites Machado Filho
2020-03-20 21:03 ` Tulio Magno Quites Machado Filho [this message]
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