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-rw-r--r--lib/lzo/lzo1x_compress.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/lib/lzo/lzo1x_compress.c b/lib/lzo/lzo1x_compress.c
index 717c940112f9..8ad5ba2b86e2 100644
--- a/lib/lzo/lzo1x_compress.c
+++ b/lib/lzo/lzo1x_compress.c
@@ -268,6 +268,19 @@ m_len_done:
*op++ = (M4_MARKER | ((m_off >> 11) & 8)
| (m_len - 2));
else {
+ if (unlikely(((m_off & 0x403f) == 0x403f)
+ && (m_len >= 261)
+ && (m_len <= 264))
+ && likely(bitstream_version)) {
+ // Under lzo-rle, block copies
+ // for 261 <= length <= 264 and
+ // (distance & 0x80f3) == 0x80f3
+ // can result in ambiguous
+ // output. Adjust length
+ // to 260 to prevent ambiguity.
+ ip -= m_len - 260;
+ m_len = 260;
+ }
m_len -= M4_MAX_LEN;
*op++ = (M4_MARKER | ((m_off >> 11) & 8));
while (unlikely(m_len > 255)) {