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[ipset,1/3] lib: data: Fix for global-buffer-overflow warning by ASAN

Message ID 20240627081818.16544-2-phil@nwl.cc
State Accepted
Headers show
Series Two fixes and fallout | expand

Commit Message

Phil Sutter June 27, 2024, 8:18 a.m. UTC 
After compiling with CFLAGS="-fsanitize=address -g", running the
testsuite triggers the following warning:

| ipmap: Range: Check syntax error: missing range/from-to: FAILED
| Failed test: ../src/ipset 2>.foo.err -N test ipmap
| =================================================================
| ==4204==ERROR: AddressSanitizer: global-buffer-overflow on address 0x55a21e77172a at pc 0x7f1ef246f2a6 bp 0x7fffed8f4f40 sp 0x7fffed8f46e8
| READ of size 32 at 0x55a21e77172a thread T0
|     #0 0x7f1ef246f2a5 in __interceptor_memcpy /var/tmp/portage/sys-devel/gcc-13.2.1_p20231014/work/gcc-13-20231014/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:899
|     #1 0x55a21e758bf6 in ipset_strlcpy /home/n0-1/git/ipset/lib/data.c:119
|     #2 0x55a21e758bf6 in ipset_data_set /home/n0-1/git/ipset/lib/data.c:349
|     #3 0x55a21e75ee2f in ipset_parse_typename /home/n0-1/git/ipset/lib/parse.c:1819
|     #4 0x55a21e754119 in ipset_parser /home/n0-1/git/ipset/lib/ipset.c:1205
|     #5 0x55a21e752cef in ipset_parse_argv /home/n0-1/git/ipset/lib/ipset.c:1344
|     #6 0x55a21e74ea45 in main /home/n0-1/git/ipset/src/ipset.c:38
|     #7 0x7f1ef224cf09  (/lib64/libc.so.6+0x23f09)
|     #8 0x7f1ef224cfc4 in __libc_start_main (/lib64/libc.so.6+0x23fc4)
|     #9 0x55a21e74f040 in _start (/home/n0-1/git/ipset/src/ipset+0x1d040)
|
| 0x55a21e77172a is located 54 bytes before global variable '*.LC1' defined in 'ipset_bitmap_ip.c' (0x55a21e771760) of size 19
|   '*.LC1' is ascii string 'IP|IP/CIDR|FROM-TO'
| 0x55a21e77172a is located 0 bytes after global variable '*.LC0' defined in 'ipset_bitmap_ip.c' (0x55a21e771720) of size 10
|   '*.LC0' is ascii string 'bitmap:ip'

Fix this by avoiding 'src' array overstep in ipset_strlcpy(): In
contrast to strncpy(), memcpy() does not respect NUL-chars in input but
stubbornly reads as many bytes as specified.

Fixes: a7432ba786ca4 ("Workaround misleading -Wstringop-truncation warning")
Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 lib/data.c | 3 +++
 1 file changed, 3 insertions(+)
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Patch

diff --git a/lib/data.c b/lib/data.c
index c05b20144cdad..64cad7a377302 100644
--- a/lib/data.c
+++ b/lib/data.c
@@ -111,6 +111,9 @@  ipset_strlcpy(char *dst, const char *src, size_t len)
 	assert(dst);
 	assert(src);
 
+	if (strlen(src) < len)
+		len = strlen(src) + 1;
+
 	memcpy(dst, src, len);
 	dst[len - 1] = '\0';
 }