From d970bad3371761555d249374e70012bba705ed73 Mon Sep 17 00:00:00 2001 From: Mark Wielaard Date: Fri, 28 Jun 2019 12:38:41 +0200 Subject: [PATCH] Be more liberal in the number of selectors we accept when decoding. As proposed by Julian Seward: * split BZ_MAX_SELECTORS into two different values: - BZ_MAX_SELECTORS_ENC = (2 + (900000 / BZ_G_SIZE)) [= 18002], the max number of selectors that bzip2 can create ("encode") - BZ_MAX_SELECTORS_DEC = BZ_MAX_SELECTORS_ENC + 6 [= 18008], the max number of selectors that we'll accept during decoding, and add a comment explaining that the difference is due to buggy lbzip2/whatever creating more than BZ_MAX_SELECTORS_ENC * use BZ_MAX_SELECTORS_ENC to dimension the arrays in struct EState * use BZ_MAX_SELECTORS_DEC to dimension the arrays in struct DState, and for the new decompress.c range check * change the compress.c assertion AssertH( nSelectors < 32768 && nSelectors <= (2 + (900000 / BZ_G_SIZE)), 3003 ); to actually mention BZ_MAX_SELECTORS_ENC directly, instead of (2 + (900000 / BZ_G_SIZE)), [which is embarrassingly lame] --- bzlib_private.h | 15 ++++++++++----- compress.c | 2 +- decompress.c | 2 +- 3 files changed, 12 insertions(+), 7 deletions(-) diff --git a/bzlib_private.h b/bzlib_private.h index 7975552..6208ba1 100644 --- a/bzlib_private.h +++ b/bzlib_private.h @@ -122,7 +122,12 @@ extern void bz_internal_error ( int errcode ); #define BZ_G_SIZE 50 #define BZ_N_ITERS 4 -#define BZ_MAX_SELECTORS (2 + (900000 / BZ_G_SIZE)) +/* The max number of selectors that bzip2 can create ("encode") [= 18002] */ +#define BZ_MAX_SELECTORS_ENC (2 + (900000 / BZ_G_SIZE)) +/* The max number of selectors that bzip2 accept during decoding [= 18008] + This is larger than BZ_MAX_SELECTORS_ENC because some implementations, + might round up the number of selectors to a factor of 8. */ +#define BZ_MAX_SELECTORS_DEC (BZ_MAX_SELECTORS_ENC + 6) @@ -253,8 +258,8 @@ typedef /* stuff for coding the MTF values */ Int32 nMTF; Int32 mtfFreq [BZ_MAX_ALPHA_SIZE]; - UChar selector [BZ_MAX_SELECTORS]; - UChar selectorMtf[BZ_MAX_SELECTORS]; + UChar selector [BZ_MAX_SELECTORS_ENC]; + UChar selectorMtf[BZ_MAX_SELECTORS_ENC]; UChar len [BZ_N_GROUPS][BZ_MAX_ALPHA_SIZE]; Int32 code [BZ_N_GROUPS][BZ_MAX_ALPHA_SIZE]; @@ -399,8 +404,8 @@ typedef /* for decoding the MTF values */ UChar mtfa [MTFA_SIZE]; Int32 mtfbase[256 / MTFL_SIZE]; - UChar selector [BZ_MAX_SELECTORS]; - UChar selectorMtf[BZ_MAX_SELECTORS]; + UChar selector [BZ_MAX_SELECTORS_DEC]; + UChar selectorMtf[BZ_MAX_SELECTORS_DEC]; UChar len [BZ_N_GROUPS][BZ_MAX_ALPHA_SIZE]; Int32 limit [BZ_N_GROUPS][BZ_MAX_ALPHA_SIZE]; diff --git a/compress.c b/compress.c index 237620d..9b660f8 100644 --- a/compress.c +++ b/compress.c @@ -454,7 +454,7 @@ void sendMTFValues ( EState* s ) AssertH( nGroups < 8, 3002 ); AssertH( nSelectors < 32768 && - nSelectors <= (2 + (900000 / BZ_G_SIZE)), + nSelectors <= BZ_MAX_SELECTORS_ENC, 3003 ); diff --git a/decompress.c b/decompress.c index 20ce493..d24a052 100644 --- a/decompress.c +++ b/decompress.c @@ -287,7 +287,7 @@ Int32 BZ2_decompress ( DState* s ) GET_BITS(BZ_X_SELECTOR_1, nGroups, 3); if (nGroups < 2 || nGroups > BZ_N_GROUPS) RETURN(BZ_DATA_ERROR); GET_BITS(BZ_X_SELECTOR_2, nSelectors, 15); - if (nSelectors < 1 || nSelectors > BZ_MAX_SELECTORS) RETURN(BZ_DATA_ERROR); + if (nSelectors < 1 || nSelectors > BZ_MAX_SELECTORS_DEC) RETURN(BZ_DATA_ERROR); for (i = 0; i < nSelectors; i++) { j = 0; while (True) { -- 1.8.3.1