[PATCH] libbacktrace: fix UBSAN issues

Martin Liška mliska@suse.cz
Thu Nov 11 15:38:47 GMT 2021


Patch can bootstrap on x86_64-linux-gnu and survives regression tests.

Ready to be installed?
Thanks,
Martin

Fix issues mentioned in the PR.

	PR libbacktrace/103167

libbacktrace/ChangeLog:

	* elf.c (elf_uncompress_lzma_block): Cast to unsigned int.
	(elf_uncompress_lzma): Likewise.
	* xztest.c (test_samples): memcpy only if v > 0.

Co-Authored-By: Andrew Pinski <apinski@marvell.com>
---
  libbacktrace/elf.c    | 8 ++++----
  libbacktrace/xztest.c | 2 +-
  2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/libbacktrace/elf.c b/libbacktrace/elf.c
index 79d56146fc6..e69ac41c88b 100644
--- a/libbacktrace/elf.c
+++ b/libbacktrace/elf.c
@@ -3175,7 +3175,7 @@ elf_uncompress_lzma_block (const unsigned char *compressed,
    stream_crc = (compressed[off]
  		| (compressed[off + 1] << 8)
  		| (compressed[off + 2] << 16)
-		| (compressed[off + 3] << 24));
+		| ((unsigned)(compressed[off + 3]) << 24));
    if (unlikely (computed_crc != stream_crc))
      {
        elf_uncompress_failed ();
@@ -3788,7 +3788,7 @@ elf_uncompress_lzma (struct backtrace_state *state,
    stream_crc = (compressed[8]
  		| (compressed[9] << 8)
  		| (compressed[10] << 16)
-		| (compressed[11] << 24));
+		| ((unsigned)(compressed[11]) << 24));
    if (unlikely (computed_crc != stream_crc))
      {
        elf_uncompress_failed ();
@@ -3832,7 +3832,7 @@ elf_uncompress_lzma (struct backtrace_state *state,
    stream_crc = (compressed[offset - 4]
  		| (compressed[offset - 3] << 8)
  		| (compressed[offset - 2] << 16)
-		| (compressed[offset - 1] << 24));
+		| ((unsigned)(compressed[offset - 1]) << 24));
    if (unlikely (computed_crc != stream_crc))
      {
        elf_uncompress_failed ();
@@ -3891,7 +3891,7 @@ elf_uncompress_lzma (struct backtrace_state *state,
    stream_crc = (compressed[offset]
  		| (compressed[offset + 1] << 8)
  		| (compressed[offset + 2] << 16)
-		| (compressed[offset + 3] << 24));
+		| ((unsigned)(compressed[offset + 3]) << 24));
    if (unlikely (computed_crc != stream_crc))
      {
        elf_uncompress_failed ();
diff --git a/libbacktrace/xztest.c b/libbacktrace/xztest.c
index b2533cb1804..6c60ff50159 100644
--- a/libbacktrace/xztest.c
+++ b/libbacktrace/xztest.c
@@ -172,7 +172,7 @@ test_samples (struct backtrace_state *state)
  		       tests[i].name, uncompressed_len, v);
  	      ++failures;
  	    }
-	  else if (memcmp (tests[i].uncompressed, uncompressed, v) != 0)
+	  else if (v > 0 && memcmp (tests[i].uncompressed, uncompressed, v) != 0)
  	    {
  	      size_t j;
  
-- 
2.33.1



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