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gh-104282: Fix null pointer dereference in lzma._decode_filter_properties (GH-104283)

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Radislav Chugunov 2024-01-17 16:15:44 +03:00 • committed by GitHub
parent b204c4beb4
commit 0154405350
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3 changed files with 14 additions and 1 deletions
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8
Lib/test/test_lzma.py
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@ -1401,6 +1401,14 @@ def test__decode_filter_properties(self):
self.assertEqual(filterspec["lc"], 3) self.assertEqual(filterspec["lc"], 3)
self.assertEqual(filterspec["dict_size"], 8 << 20) self.assertEqual(filterspec["dict_size"], 8 << 20)
# see gh-104282
filters = [lzma.FILTER_X86, lzma.FILTER_POWERPC,
lzma.FILTER_IA64, lzma.FILTER_ARM,
lzma.FILTER_ARMTHUMB, lzma.FILTER_SPARC]
for f in filters:
filterspec = lzma._decode_filter_properties(f, b"")
self.assertEqual(filterspec, {"id": f})
def test_filter_properties_roundtrip(self): def test_filter_properties_roundtrip(self):
spec1 = lzma._decode_filter_properties( spec1 = lzma._decode_filter_properties(
lzma.FILTER_LZMA1, b"]\x00\x00\x80\x00") lzma.FILTER_LZMA1, b"]\x00\x00\x80\x00")

3
Misc/NEWS.d/next/Library/2023-05-08-09-30-00.gh-issue-104282.h4c6Eb.rst Normal file
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@ -0,0 +1,3 @@
Fix null pointer dereference in :func:`lzma._decode_filter_properties`
due to improper handling of BCJ filters with properties of zero length.
Patch by Radislav Chugunov.

4
Modules/_lzmamodule.c
View file

@ -492,7 +492,9 @@ build_filter_spec(const lzma_filter *f)
case LZMA_FILTER_ARMTHUMB: case LZMA_FILTER_ARMTHUMB:
case LZMA_FILTER_SPARC: { case LZMA_FILTER_SPARC: {
lzma_options_bcj *options = f->options; lzma_options_bcj *options = f->options;
ADD_FIELD(options, start_offset); if (options) {
ADD_FIELD(options, start_offset);
}
break; break;
} }
default: default: