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busybox-1.27.2: Fix CVE-2017-15873
[No upstream tracking] -- https://bugs.busybox.net/show_bug.cgi?id=10431
bunzip2: fix runCnt overflow
The get_next_block function in archival/libarchive/decompress_bunzip2.c
in BusyBox 1.27.2 has an Integer Overflow that may lead to a write
access violation.
Upstream-Status: Backport [https://git.busybox.net/busybox/commit/?id=0402cb32df015d9372578e3db27db47b33d5c7b0]
CVE: CVE-2017-15873
bug: 10431
Signed-off-by: Radovan Scasny <radovan.scasny@siemens.com>
diff --git a/archival/libarchive/decompress_bunzip2.c b/archival/libarchive/decompress_bunzip2.c
index 7cd18f5..bec89ed 100644
--- a/archival/libarchive/decompress_bunzip2.c
+++ b/archival/libarchive/decompress_bunzip2.c
@@ -156,15 +156,15 @@ static unsigned get_bits(bunzip_data *bd, int bits_wanted)
static int get_next_block(bunzip_data *bd)
{
struct group_data *hufGroup;
- int dbufCount, dbufSize, groupCount, *base, *limit, selector,
- i, j, runPos, symCount, symTotal, nSelectors, byteCount[256];
- int runCnt = runCnt; /* for compiler */
+ int groupCount, *base, *limit, selector,
+ i, j, symCount, symTotal, nSelectors, byteCount[256];
uint8_t uc, symToByte[256], mtfSymbol[256], *selectors;
uint32_t *dbuf;
unsigned origPtr, t;
+ unsigned dbufCount, runPos;
+ unsigned runCnt = runCnt; /* for compiler */
dbuf = bd->dbuf;
- dbufSize = bd->dbufSize;
selectors = bd->selectors;
/* In bbox, we are ok with aborting through setjmp which is set up in start_bunzip */
@@ -187,7 +187,7 @@ static int get_next_block(bunzip_data *bd)
it didn't actually work. */
if (get_bits(bd, 1)) return RETVAL_OBSOLETE_INPUT;
origPtr = get_bits(bd, 24);
- if ((int)origPtr > dbufSize) return RETVAL_DATA_ERROR;
+ if (origPtr > bd->dbufSize) return RETVAL_DATA_ERROR;
/* mapping table: if some byte values are never used (encoding things
like ascii text), the compression code removes the gaps to have fewer
@@ -435,7 +435,14 @@ static int get_next_block(bunzip_data *bd)
symbols, but a run of length 0 doesn't mean anything in this
context). Thus space is saved. */
runCnt += (runPos << nextSym); /* +runPos if RUNA; +2*runPos if RUNB */
- if (runPos < dbufSize) runPos <<= 1;
+//The 32-bit overflow of runCnt wasn't yet seen, but probably can happen.
+//This would be the fix (catches too large count way before it can overflow):
+// if (runCnt > bd->dbufSize) {
+// dbg("runCnt:%u > dbufSize:%u RETVAL_DATA_ERROR",
+// runCnt, bd->dbufSize);
+// return RETVAL_DATA_ERROR;
+// }
+ if (runPos < bd->dbufSize) runPos <<= 1;
goto end_of_huffman_loop;
}
@@ -445,14 +452,15 @@ static int get_next_block(bunzip_data *bd)
literal used is the one at the head of the mtfSymbol array.) */
if (runPos != 0) {
uint8_t tmp_byte;
- if (dbufCount + runCnt > dbufSize) {
- dbg("dbufCount:%d+runCnt:%d %d > dbufSize:%d RETVAL_DATA_ERROR",
- dbufCount, runCnt, dbufCount + runCnt, dbufSize);
+ if (dbufCount + runCnt > bd->dbufSize) {
+ dbg("dbufCount:%u+runCnt:%u %u > dbufSize:%u RETVAL_DATA_ERROR",
+ dbufCount, runCnt, dbufCount + runCnt, bd->dbufSize);
return RETVAL_DATA_ERROR;
}
tmp_byte = symToByte[mtfSymbol[0]];
byteCount[tmp_byte] += runCnt;
- while (--runCnt >= 0) dbuf[dbufCount++] = (uint32_t)tmp_byte;
+ while ((int)--runCnt >= 0)
+ dbuf[dbufCount++] = (uint32_t)tmp_byte;
runPos = 0;
}
@@ -466,7 +474,7 @@ static int get_next_block(bunzip_data *bd)
first symbol in the mtf array, position 0, would have been handled
as part of a run above. Therefore 1 unused mtf position minus
2 non-literal nextSym values equals -1.) */
- if (dbufCount >= dbufSize) return RETVAL_DATA_ERROR;
+ if (dbufCount >= bd->dbufSize) return RETVAL_DATA_ERROR;
i = nextSym - 1;
uc = mtfSymbol[i];
--
cgit v0.12
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