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Introduced conf_lzma.max_num_probs to limit stack size for decompression.

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This commit is contained in:
Markus F.X.J. Oberhumer 2006-06-29 05:12:01 +02:00
parent c360806f47
commit 0bc361adeb
2 changed files with 36 additions and 14 deletions
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40
src/compress_lzma.cpp
View File

@ -160,7 +160,6 @@ int upx_lzma_compress ( const upx_bytep src, unsigned src_len,
{
assert(method == M_LZMA);
assert(level > 0); assert(result != NULL);
UNUSED(conf_parm);
int r = UPX_E_ERROR;
HRESULT rh;
@ -189,13 +188,20 @@ int upx_lzma_compress ( const upx_bytep src, unsigned src_len,
pr[4].vt = pr[5].vt = pr[6].vt = VT_UI4;
// setup defaults
pr[0].uintVal = 2;
pr[1].uintVal = 0;
pr[2].uintVal = 3;
pr[0].uintVal = 2; // 0..4
pr[1].uintVal = 0; // 0..4
pr[2].uintVal = 3; // 0..8
pr[3].uintVal = 1024 * 1024;
pr[4].uintVal = 2;
pr[5].uintVal = 64;
pr[5].uintVal = 64; // 5..
pr[6].uintVal = 0;
#if 1
// DEBUG - set sizes so that we use a maxmimum amount of stack
// these settings cause res->num_probs == 3147574, i.e. we will
// need about 6 MB of stack
pr[1].uintVal = 4;
pr[2].uintVal = 8;
#endif
// FIXME: tune these settings according to level
switch (level)
@ -228,9 +234,33 @@ int upx_lzma_compress ( const upx_bytep src, unsigned src_len,
goto error;
}
// limit dictionary size
if (pr[3].uintVal > src_len)
pr[3].uintVal = src_len;
// limit num_probs
if (conf_parm && conf_parm->conf_lzma.max_num_probs)
{
for (;;)
{
unsigned n = 1846 + (768 << (pr[2].uintVal + pr[1].uintVal));
if (n <= conf_parm->conf_lzma.max_num_probs)
break;
if (pr[1].uintVal > pr[2].uintVal)
{
if (pr[1].uintVal == 0)
goto error;
pr[1].uintVal -= 1;
}
else
{
if (pr[2].uintVal == 0)
goto error;
pr[2].uintVal -= 1;
}
}
}
res->pos_bits = pr[0].uintVal;
res->lit_pos_bits = pr[1].uintVal;
res->lit_context_bits = pr[2].uintVal;

10
src/conf.h
View File

@ -210,15 +210,7 @@ struct upx_callback_t
struct lzma_compress_config_t
{
#if 0
unsigned pos_bits; // pb
unsigned lit_pos_bits; // lp
unsigned lit_context_bits; // lc
unsigned dict_size;
unsigned mf_passes;
#else
int dummy;
#endif
unsigned max_num_probs;
void reset() { memset(this, 0, sizeof(*this)); }
};