unlzma: fix segfault on bad archive

function                                             old     new   delta
unpack_lzma_stream                                  2647    2653      +6

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/archival/libarchive/decompress_unlzma.c b/archival/libarchive/decompress_unlzma.c
index be4342414..80a453806 100644
--- a/archival/libarchive/decompress_unlzma.c
+++ b/archival/libarchive/decompress_unlzma.c
@@ -11,6 +11,13 @@
 #include "libbb.h"
 #include "bb_archive.h"
 
+#if 0
+# define dbg(...) bb_error_msg(__VA_ARGS__)
+#else
+# define dbg(...) ((void)0)
+#endif
+
+
 #if ENABLE_FEATURE_LZMA_FAST
 #  define speed_inline ALWAYS_INLINE
 #  define size_inline
@@ -417,6 +424,10 @@ unpack_lzma_stream(transformer_state_t *xstate)
                                                 for (; num_bits2 != LZMA_NUM_ALIGN_BITS; num_bits2--)
                                                         rep0 = (rep0 << 1) | rc_direct_bit(rc);
                                                 rep0 <<= LZMA_NUM_ALIGN_BITS;
+                                                if ((int32_t)rep0 < 0) {
+                                                        dbg("%d rep0:%d", __LINE__, rep0);
+                                                        goto bad;
+                                                }
                                                 prob3 = p + LZMA_ALIGN;
                                         }
                                         i2 = 1;