" Paulo Alcantara (SUSE) " <paulo@xxxxxxxx> writes:
> It can be easily reproduced with the following:
>
> # chmod +s `which mount.cifs`
> # echo "//localhost/share /mnt cifs \
> users,username=foo,password=XXXX" >> /etc/fstab
> # su - foo
> $ mount /mnt
> free(): double free detected in tcache 2
> Child process terminated abnormally.
>
> The problem was that check_fstab() already freed orgoptions pointer
> and then we freed it again in main() function.
>
> Fixes: bf7f48f4c7dc ("mount.cifs.c: fix memory leaks in main func")
> Signed-off-by: Paulo Alcantara (SUSE) <paulo@xxxxxxxx>
Reviewed-by: Aurelien Aptel <aaptel@xxxxxxxx>
I've compiled next branch with ASAN and can confirm the double-free and
the fix works
Compiling with ASAN
-------------------
$ CFLAGS=-fsanitize=address \
LDFLAGS=-fsanitize=address \
ac_cv_func_malloc_0_nonnull=yes \
./configure
$ make clean && make -j4
Next branch
-----------
$ mount /mnt; echo $?
=================================================================
==29883==ERROR: AddressSanitizer: attempting double-free on 0x607000000020 in thread T0:
#0 0x7f69d480a1b8 in __interceptor_free (/usr/lib64/libasan.so.4+0xdc1b8)
#1 0x559381795f33 in main (/sbin/mount.cifs+0xef33)
#2 0x7f69d4394f89 in __libc_start_main (/lib64/libc.so.6+0x20f89)
#3 0x55938178e079 in _start (/sbin/mount.cifs+0x7079)
0x607000000020 is located 0 bytes inside of 68-byte region [0x607000000020,0x607000000064)
freed by thread T0 here:
#0 0x7f69d480a1b8 in __interceptor_free (/usr/lib64/libasan.so.4+0xdc1b8)
#1 0x55938178e372 in check_fstab (/sbin/mount.cifs+0x7372)
#2 0x559381794661 in assemble_mountinfo (/sbin/mount.cifs+0xd661)
#3 0x559381795eef in main (/sbin/mount.cifs+0xeeef)
#4 0x7f69d4394f89 in __libc_start_main (/lib64/libc.so.6+0x20f89)
previously allocated by thread T0 here:
#0 0x7f69d480a510 in malloc (/usr/lib64/libasan.so.4+0xdc510)
#1 0x7f69d43fc2a9 in __GI___strndup (/lib64/libc.so.6+0x882a9)
SUMMARY: AddressSanitizer: double-free (/usr/lib64/libasan.so.4+0xdc1b8) in __interceptor_free
==29883==ABORTING
1
With fix
--------
$ mount /mnt; echo $?
0
Cheers,
--
Aurélien Aptel / SUSE Labs Samba Team
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