compression/huffman: debug function bails upon disaster (CID 1517261)

We shouldn't get a node with a zero code, and there's probably nothing to do but stop. CID 1517261 (#1-2 of 2): Bad bit shift operation (BAD_SHIFT)11. negative_shift: In expression j >> offset - k, shifting by a negative amount has undefined behavior. The shift amount, offset - k, is -3. Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz> Reviewed-by: Jeremy Allison <jra@samba.org> Autobuild-User(master): Jeremy Allison <jra@samba.org> Autobuild-Date(master): Mon Dec 19 23:29:04 UTC 2022 on sn-devel-184
samba-team · Dec 19, 2022 · 44a4400 · 44a4400
1 parent 628f14c
commit 44a4400
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/lib/compression/lzxpress_huffman.c b/lib/compression/lzxpress_huffman.c
@@ -1390,6 +1390,11 @@ static void debug_tree_codes(struct bitstream *input)
 			int k;
 			uint16_t j = q.code_code;
 			size_t offset = bitlen_nonzero_16(j) - 1;
+			if (unlikely(j == 0)) {
+				DBG("BROKEN code is 0!\n");
+				return;
+			}
+
 			for (k = 0; k <= offset; k++) {
 				bool b = (j >> (offset - k)) & 1;
 				bits[k] = b ? '1' : '0';