From d48a8d61c07e3841ffd71f3aafa5db28dd35b6a7 Mon Sep 17 00:00:00 2001 From: "Paulo Alcantara (SUSE)" Date: Thu, 19 Sep 2019 08:35:47 -0300 Subject: [PATCH] mount.cifs: Fix invalid free When attemping to chdir into non-existing directories, mount.cifs crashes. This patch fixes the following ASAN report: $ ./mount.cifs //localhost/foo /mnt/invalid-dir -o ... /mnt/bar -o username=foo,password=foo,vers=1.0 Couldn't chdir to /mnt/bar: No such file or directory ================================================================= ==11846==ERROR: AddressSanitizer: attempting free on address which was not malloc()-ed: 0x7ffd86332e97 in thread T0 #0 0x7f0860ca01e7 in __interceptor_free (/usr/lib64/libasan.so.5+0x10a1e7) #1 0x557edece9ccb in acquire_mountpoint (/home/paulo/src/cifs-utils/mount.cifs+0xeccb) #2 0x557edecea63d in main (/home/paulo/src/cifs-utils/mount.cifs+0xf63d) #3 0x7f08609f0bca in __libc_start_main (/lib64/libc.so.6+0x26bca) #4 0x557edece27d9 in _start (/home/paulo/src/cifs-utils/mount.cifs+0x77d9) Address 0x7ffd86332e97 is located in stack of thread T0 at offset 8951 in frame #0 0x557edece9ce0 in main (/home/paulo/src/cifs-utils/mount.cifs+0xece0) This frame has 2 object(s): [48, 52) 'rc' (line 1959) [64, 72) 'mountpoint' (line 1955) <== Memory access at offset 8951 overflows this variable HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork (longjmp and C++ exceptions *are* supported) SUMMARY: AddressSanitizer: bad-free (/usr/lib64/libasan.so.5+0x10a1e7) in __interceptor_free ==11846==ABORTING Fixes: bf7f48f4c7dc ("mount.cifs.c: fix memory leaks in main func") Signed-off-by: Paulo Alcantara (SUSE) --- mount.cifs.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/mount.cifs.c b/mount.cifs.c index 7748d54aa814..0c38adcd99b1 100644 --- a/mount.cifs.c +++ b/mount.cifs.c @@ -1893,7 +1893,7 @@ acquire_mountpoint(char **mountpointp) int rc, dacrc; uid_t realuid, oldfsuid; gid_t oldfsgid; - char *mountpoint; + char *mountpoint = NULL; /* * Acquire the necessary privileges to chdir to the mountpoint. If @@ -1942,9 +1942,9 @@ restore_privs: gid_t __attribute__((unused)) gignore = setfsgid(oldfsgid); } - if (rc) { - free(*mountpointp); - } + if (rc) + free(mountpoint); + return rc; } -- 2.23.0