Message ID | 20190901183401.29040-1-pepe.schlehofer@gmail.com |
---|---|
State | Accepted |
Headers | show |
Series | [OpenWrt-Devel] bzip2: Fix CVE-2019-12900 | expand |
On Sun, Sep 1, 2019 at 11:34 AM Josef Schlehofer <pepe.schlehofer@gmail.com> wrote: > > More details about this CVE: > https://nvd.nist.gov/vuln/detail/CVE-2019-12900 > > Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com> > --- This is for 18.06. Usually notes like that are placed here below the --- line. > package/utils/bzip2/Makefile | 2 +- > .../bzip2/patches/020-CVE-2019-12900.patch | 65 +++++++++++++++++++ > 2 files changed, 66 insertions(+), 1 deletion(-) > create mode 100644 package/utils/bzip2/patches/020-CVE-2019-12900.patch > > diff --git a/package/utils/bzip2/Makefile b/package/utils/bzip2/Makefile > index ea2fc76833..0bf168c229 100644 > --- a/package/utils/bzip2/Makefile > +++ b/package/utils/bzip2/Makefile > @@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk > > PKG_NAME:=bzip2 > PKG_VERSION:=1.0.6 > -PKG_RELEASE:=4 > +PKG_RELEASE:=5 > > PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz > PKG_SOURCE_URL:=http://www.bzip.org/$(PKG_VERSION) > diff --git a/package/utils/bzip2/patches/020-CVE-2019-12900.patch b/package/utils/bzip2/patches/020-CVE-2019-12900.patch > new file mode 100644 > index 0000000000..3f08c789ea > --- /dev/null > +++ b/package/utils/bzip2/patches/020-CVE-2019-12900.patch > @@ -0,0 +1,65 @@ > +From 812a898b7622de90e98f103ff7fed0984e4548e4 Mon Sep 17 00:00:00 2001 > +From: Mark Wielaard <mark@klomp.org> > +Date: Wed, 3 Jul 2019 01:28:11 +0200 > +Subject: [PATCH] Accept as many selectors as the file format allows. > + > +But ignore any larger than the theoretical maximum, BZ_MAX_SELECTORS. > + > +The theoretical maximum number of selectors depends on the maximum > +blocksize (900000 bytes) and the number of symbols (50) that can be > +encoded with a different Huffman tree. BZ_MAX_SELECTORS is 18002. > + > +But the bzip2 file format allows the number of selectors to be encoded > +with 15 bits (because 18002 isn't a factor of 2 and doesn't fit in > +14 bits). So the file format maximum is 32767 selectors. > + > +Some bzip2 encoders might actually have written out more selectors > +than the theoretical maximum because they rounded up the number of > +selectors to some convenient factor of 8. > + > +The extra 14766 selectors can never be validly used by the decompression > +algorithm. So we can read them, but then discard them. > + > +This is effectively what was done (by accident) before we added a > +check for nSelectors to be at most BZ_MAX_SELECTORS to mitigate > +CVE-2019-12900. > + > +The extra selectors were written out after the array inside the > +EState struct. But the struct has extra space allocated after the > +selector arrays of 18060 bytes (which is larger than 14766). > +All of which will be initialized later (so the overwrite of that > +space with extra selector values would have been harmless). > +--- > + compress.c | 2 +- > + decompress.c | 10 +++++++- > + 2 files changed, 8 insertions(+), 2 deletions(-) > + > +--- 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, > + 3003 ); > + > + > +--- a/decompress.c > ++++ b/decompress.c > +@@ -296,8 +296,14 @@ Int32 BZ2_decompress ( DState* s ) > + j++; > + if (j >= nGroups) RETURN(BZ_DATA_ERROR); > + } > +- s->selectorMtf[i] = j; > ++ /* Having more than BZ_MAX_SELECTORS doesn't make much sense > ++ since they will never be used, but some implementations might > ++ "round up" the number of selectors, so just ignore those. */ > ++ if (i < BZ_MAX_SELECTORS) > ++ s->selectorMtf[i] = j; > + } > ++ if (nSelectors > BZ_MAX_SELECTORS) > ++ nSelectors = BZ_MAX_SELECTORS; > + > + /*--- Undo the MTF values for the selectors. ---*/ > + { > -- > 2.20.1 > > > _______________________________________________ > openwrt-devel mailing list > openwrt-devel@lists.openwrt.org > https://lists.openwrt.org/mailman/listinfo/openwrt-devel
Merged into openwrt-18.06. Thank you!
diff --git a/package/utils/bzip2/Makefile b/package/utils/bzip2/Makefile index ea2fc76833..0bf168c229 100644 --- a/package/utils/bzip2/Makefile +++ b/package/utils/bzip2/Makefile @@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk PKG_NAME:=bzip2 PKG_VERSION:=1.0.6 -PKG_RELEASE:=4 +PKG_RELEASE:=5 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz PKG_SOURCE_URL:=http://www.bzip.org/$(PKG_VERSION) diff --git a/package/utils/bzip2/patches/020-CVE-2019-12900.patch b/package/utils/bzip2/patches/020-CVE-2019-12900.patch new file mode 100644 index 0000000000..3f08c789ea --- /dev/null +++ b/package/utils/bzip2/patches/020-CVE-2019-12900.patch @@ -0,0 +1,65 @@ +From 812a898b7622de90e98f103ff7fed0984e4548e4 Mon Sep 17 00:00:00 2001 +From: Mark Wielaard <mark@klomp.org> +Date: Wed, 3 Jul 2019 01:28:11 +0200 +Subject: [PATCH] Accept as many selectors as the file format allows. + +But ignore any larger than the theoretical maximum, BZ_MAX_SELECTORS. + +The theoretical maximum number of selectors depends on the maximum +blocksize (900000 bytes) and the number of symbols (50) that can be +encoded with a different Huffman tree. BZ_MAX_SELECTORS is 18002. + +But the bzip2 file format allows the number of selectors to be encoded +with 15 bits (because 18002 isn't a factor of 2 and doesn't fit in +14 bits). So the file format maximum is 32767 selectors. + +Some bzip2 encoders might actually have written out more selectors +than the theoretical maximum because they rounded up the number of +selectors to some convenient factor of 8. + +The extra 14766 selectors can never be validly used by the decompression +algorithm. So we can read them, but then discard them. + +This is effectively what was done (by accident) before we added a +check for nSelectors to be at most BZ_MAX_SELECTORS to mitigate +CVE-2019-12900. + +The extra selectors were written out after the array inside the +EState struct. But the struct has extra space allocated after the +selector arrays of 18060 bytes (which is larger than 14766). +All of which will be initialized later (so the overwrite of that +space with extra selector values would have been harmless). +--- + compress.c | 2 +- + decompress.c | 10 +++++++- + 2 files changed, 8 insertions(+), 2 deletions(-) + +--- 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, + 3003 ); + + +--- a/decompress.c ++++ b/decompress.c +@@ -296,8 +296,14 @@ Int32 BZ2_decompress ( DState* s ) + j++; + if (j >= nGroups) RETURN(BZ_DATA_ERROR); + } +- s->selectorMtf[i] = j; ++ /* Having more than BZ_MAX_SELECTORS doesn't make much sense ++ since they will never be used, but some implementations might ++ "round up" the number of selectors, so just ignore those. */ ++ if (i < BZ_MAX_SELECTORS) ++ s->selectorMtf[i] = j; + } ++ if (nSelectors > BZ_MAX_SELECTORS) ++ nSelectors = BZ_MAX_SELECTORS; + + /*--- Undo the MTF values for the selectors. ---*/ + {
More details about this CVE: https://nvd.nist.gov/vuln/detail/CVE-2019-12900 Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com> --- package/utils/bzip2/Makefile | 2 +- .../bzip2/patches/020-CVE-2019-12900.patch | 65 +++++++++++++++++++ 2 files changed, 66 insertions(+), 1 deletion(-) create mode 100644 package/utils/bzip2/patches/020-CVE-2019-12900.patch