samba-bugs at samba.org
2017-Oct-31 04:03 UTC
[Bug 13112] New: receive_xattr heap overread with non null terminated name and xattr filter
https://bugzilla.samba.org/show_bug.cgi?id=13112
Bug ID: 13112
Summary: receive_xattr heap overread with non null terminated
name and xattr filter
Product: rsync
Version: 3.1.3
Hardware: All
OS: All
Status: NEW
Severity: normal
Priority: P5
Component: core
Assignee: wayned at samba.org
Reporter: jeriko.one at gmx.us
QA Contact: rsync-qa at samba.org
Created attachment 13744
--> https://bugzilla.samba.org/attachment.cgi?id=13744&action=edit
Make room for trailing NULL and use read_sbuf
$ ./rsync -v
rsync version 3.1.3dev protocol version 31
code snippets are from receive_xattr in xattrs.c
in receive_xattr a name is read from the sender. The sender sends the length of
the name, and then sends the name. The name is read in via read_buf so it's
not
null terminated.
815 size_t name_len = read_varint(f);
826 read_buf(f, name, name_len);
If the sender sent --filter that had an xattr filter then this name will be
passed to name_is_excluded.
834 if (saw_xattr_filter) {
835 if (name_is_excluded(name, NAME_IS_XATTR, ALL_FILTERS)) {
This can lead to a heap overread as name_is_excluded is expecting a NULL
terminated string.
These are the arguments I'm sending to the daemon when connecting
{"--server", "--filter", "+x jk", "-X",
".", ".", "\0"};
I provided a patch that will make room for a NULL byte in name, and use
read_sbuf instead.
ASan output:
==================================================================3497==ERROR:
AddressSanitizer: heap-buffer-overflow on address 0x60200000e831
at pc 0x7ffff6edc15b bp 0x7fffffff9990 sp 0x7fffffff9138
READ of size 2 at 0x60200000e831 thread T0
#0 0x7ffff6edc15a in strlen
(/usr/lib/gcc/x86_64-pc-linux-gnu/5.4.0/libasan.so.2+0x7015a)
#1 0x4412dd in rule_matches /home/raj/rsync/rsync/exclude.c:696
#2 0x441921 in check_filter /home/raj/rsync/rsync/exclude.c:772
#3 0x441724 in name_is_excluded /home/raj/rsync/rsync/exclude.c:744
#4 0x4a2d76 in receive_xattr /home/raj/rsync/rsync/xattrs.c:835
#5 0x40beac in recv_file_entry /home/raj/rsync/rsync/flist.c:1108
#6 0x415bee in recv_file_list /home/raj/rsync/rsync/flist.c:2476
#7 0x454eaa in do_server_recv /home/raj/rsync/rsync/main.c:1036
#8 0x4556f4 in start_server /home/raj/rsync/rsync/main.c:1115
#9 0x4b20f2 in rsync_module /home/raj/rsync/rsync/clientserver.c:1007
#10 0x4b2b11 in start_daemon /home/raj/rsync/rsync/clientserver.c:1135
#11 0x48f636 in start_accept_loop /home/raj/rsync/rsync/socket.c:618
#12 0x4b32d2 in daemon_main /home/raj/rsync/rsync/clientserver.c:1237
#13 0x458318 in main /home/raj/rsync/rsync/main.c:1630
#14 0x7ffff64d866f in __libc_start_main (/lib64/libc.so.6+0x2066f)
#15 0x4047c8 in _start (/home/raj/rsync/asan/bin/rsync+0x4047c8)
0x60200000e831 is located 0 bytes to the right of 1-byte region
[0x60200000e830,0x60200000e831)
allocated by thread T0 here:
#0 0x7ffff6f04572 in malloc
(/usr/lib/gcc/x86_64-pc-linux-gnu/5.4.0/libasan.so.2+0x98572)
#1 0x44e48b in _new_array /home/raj/rsync/rsync/util2.c:68
#2 0x4a2c63 in receive_xattr /home/raj/rsync/rsync/xattrs.c:822
#3 0x40beac in recv_file_entry /home/raj/rsync/rsync/flist.c:1108
#4 0x415bee in recv_file_list /home/raj/rsync/rsync/flist.c:2476
#5 0x454eaa in do_server_recv /home/raj/rsync/rsync/main.c:1036
#6 0x4556f4 in start_server /home/raj/rsync/rsync/main.c:1115
#7 0x4b20f2 in rsync_module /home/raj/rsync/rsync/clientserver.c:1007
#8 0x4b2b11 in start_daemon /home/raj/rsync/rsync/clientserver.c:1135
#9 0x48f636 in start_accept_loop /home/raj/rsync/rsync/socket.c:618
#10 0x4b32d2 in daemon_main /home/raj/rsync/rsync/clientserver.c:1237
#11 0x458318 in main /home/raj/rsync/rsync/main.c:1630
#12 0x7ffff64d866f in __libc_start_main (/lib64/libc.so.6+0x2066f)
SUMMARY: AddressSanitizer: heap-buffer-overflow ??:0 strlen
Shadow bytes around the buggy address:
0x0c047fff9cb0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9cc0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9cd0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9ce0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9cf0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c047fff9d00: fa fa fa fa fa fa[01]fa fa fa 04 fa fa fa 00 07
0x0c047fff9d10: fa fa fd fd fa fa 02 fa fa fa 02 fa fa fa 00 01
0x0c047fff9d20: fa fa 03 fa fa fa 06 fa fa fa 00 01 fa fa 06 fa
0x0c047fff9d30: fa fa 00 01 fa fa 06 fa fa fa fd fd fa fa fd fa
0x0c047fff9d40: fa fa 00 01 fa fa fd fa fa fa fd fa fa fa 00 01
0x0c047fff9d50: fa fa fd fa fa fa fd fa fa fa 02 fa fa fa fd fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Heap right redzone: fb
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack partial redzone: f4
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
==3497==ABORTING
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samba-bugs at samba.org
2017-Oct-31 18:46 UTC
[Bug 13112] receive_xattr heap overread with non null terminated name and xattr filter
https://bugzilla.samba.org/show_bug.cgi?id=13112
--- Comment #1 from jeriko.one at gmx.us ---
This issue can also be reached in 3.1.2, but through a different path as the
earlier version doesn't have an xattr filter. I believe the same fix for
3.1.3
would work for 3.1.2 (using read_sbuf) If I should open a separate bug for this
please let me know.
It requires the daemon to use:
fake super = yes
so that am_root == -1
the sender needs to send at least 2 xattrs, at least one without the
USER_PREFIX, and one that doesn't have a terminating NULL.
same issue of name being read in with read_buf, so it's not guaranteed to be
NULL terminated.
698 read_buf(f, name, name_len);
705 #ifdef HAVE_LINUX_XATTRS
706 /* Non-root can only save the user namespace. */
707 if (am_root <= 0 && !HAS_PREFIX(name, USER_PREFIX)) {
708 if (!am_root) {
709 free(ptr);
710 continue;
711 }
712 name -= RPRE_LEN;
713 name_len += RPRE_LEN;
714 memcpy(name, RSYNC_PREFIX, RPRE_LEN);
715 need_sort = 1;
716 }
After reading the xattrs it'll sort them if need be. need_sort is set in the
previous code snippet.
747 if (need_sort && count > 1)
748 qsort(temp_xattr.items, count, sizeof (rsync_xa),
rsync_xal_compare_names);
116 static int rsync_xal_compare_names(const void *x1, const void *x2)
117 {
118 const rsync_xa *xa1 = x1;
119 const rsync_xa *xa2 = x2;
120 return strcmp(xa1->name, xa2->name);
121 }
rsync_xal_compare_names is expecting the names to be NULL terminated, but that
isn't guaranteed.
ASan output:
==================================================================29001==ERROR:
AddressSanitizer: heap-buffer-overflow on address
0x60200000eaa0 at pc 0x7ffff6eb3185 bp 0x7fffffff99d0 sp 0x7fffffff9178
READ of size 18 at 0x60200000eaa0 thread T0
#0 0x7ffff6eb3184
(/usr/lib/gcc/x86_64-pc-linux-gnu/5.4.0/libasan.so.2+0x47184)
#1 0x49b7e6 in rsync_xal_compare_names
/home/raj/rsync/rsync-3.1.2/xattrs.c:120
#2 0x7ffff64ecc9b (/lib64/libc.so.6+0x34c9b)
#3 0x7ffff64ecfe9 in qsort_r (/lib64/libc.so.6+0x34fe9)
#4 0x49f443 in receive_xattr /home/raj/rsync/rsync-3.1.2/xattrs.c:748
#5 0x40be5b in recv_file_entry /home/raj/rsync/rsync-3.1.2/flist.c:1126
#6 0x415b95 in recv_file_list /home/raj/rsync/rsync-3.1.2/flist.c:2494
#7 0x45478f in do_server_recv /home/raj/rsync/rsync-3.1.2/main.c:1025
#8 0x454fd9 in start_server /home/raj/rsync/rsync-3.1.2/main.c:1104
#9 0x4ae074 in rsync_module /home/raj/rsync/rsync-3.1.2/clientserver.c:1003
#10 0x4ae68a in start_daemon
/home/raj/rsync/rsync-3.1.2/clientserver.c:1094
#11 0x48e271 in start_accept_loop /home/raj/rsync/rsync-3.1.2/socket.c:618
#12 0x4aee41 in daemon_main /home/raj/rsync/rsync-3.1.2/clientserver.c:1196
#13 0x457c02 in main /home/raj/rsync/rsync-3.1.2/main.c:1621
#14 0x7ffff64d866f in __libc_start_main (/lib64/libc.so.6+0x2066f)
#15 0x404778 in _start (/home/raj/rsync/release_asan/bin/rsync+0x404778)
0x60200000eaa0 is located 0 bytes to the right of 16-byte region
[0x60200000ea90,0x60200000eaa0)
allocated by thread T0 here:
#0 0x7ffff6f04572 in malloc
(/usr/lib/gcc/x86_64-pc-linux-gnu/5.4.0/libasan.so.2+0x98572)
#1 0x44ddad in _new_array /home/raj/rsync/rsync-3.1.2/util2.c:70
#2 0x49f012 in receive_xattr /home/raj/rsync/rsync-3.1.2/xattrs.c:694
#3 0x40be5b in recv_file_entry /home/raj/rsync/rsync-3.1.2/flist.c:1126
#4 0x415b95 in recv_file_list /home/raj/rsync/rsync-3.1.2/flist.c:2494
#5 0x45478f in do_server_recv /home/raj/rsync/rsync-3.1.2/main.c:1025
#6 0x454fd9 in start_server /home/raj/rsync/rsync-3.1.2/main.c:1104
#7 0x4ae074 in rsync_module /home/raj/rsync/rsync-3.1.2/clientserver.c:1003
#8 0x4ae68a in start_daemon /home/raj/rsync/rsync-3.1.2/clientserver.c:1094
#9 0x48e271 in start_accept_loop /home/raj/rsync/rsync-3.1.2/socket.c:618
#10 0x4aee41 in daemon_main /home/raj/rsync/rsync-3.1.2/clientserver.c:1196
#11 0x457c02 in main /home/raj/rsync/rsync-3.1.2/main.c:1621
#12 0x7ffff64d866f in __libc_start_main (/lib64/libc.so.6+0x2066f)
SUMMARY: AddressSanitizer: heap-buffer-overflow ??:0 ??
Shadow bytes around the buggy address:
0x0c047fff9d00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9d10: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9d20: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9d30: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9d40: fa fa fa fa fa fa fa fa fa fa fa fa fa fa 00 00
=>0x0c047fff9d50: fa fa 00 00[fa]fa 04 fa fa fa 00 07 fa fa fd fd
0x0c047fff9d60: fa fa 02 fa fa fa 02 fa fa fa 00 01 fa fa 00 01
0x0c047fff9d70: fa fa 06 fa fa fa fd fd fa fa fd fa fa fa 02 fa
0x0c047fff9d80: fa fa fd fa fa fa fd fa fa fa fd fa fa fa fd fa
0x0c047fff9d90: fa fa 02 fa fa fa 03 fa fa fa 00 01 fa fa fd fd
0x0c047fff9da0: fa fa 00 04 fa fa fd fd fa fa fd fd fa fa fd fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Heap right redzone: fb
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack partial redzone: f4
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
==29001==ABORTING
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samba-bugs at samba.org
2017-Nov-05 19:48 UTC
[Bug 13112] receive_xattr heap overread with non null terminated name
https://bugzilla.samba.org/show_bug.cgi?id=13112
Wayne Davison <wayned at samba.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
--- Comment #2 from Wayne Davison <wayned at samba.org> ---
The name_len value is set to include the terminating null char, e.g.:
name_len = strlen(name) + 1;
I tweaked the read code to validate that the read value is null-terminated, and
die if it is not.
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