Fix CVE-2017-2620: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-2620 https://lists.gnu.org/archive/html/qemu-devel/2017-02/msg04700.html Both patches copied from upstream source repository: Fixes CVE-2017-2620: http://git.qemu-project.org/?p=qemu.git;a=commit;h=92f2b88cea48c6aeba8de568a45f2ed958f3c298 The CVE-2017-2620 bug-fix depends on this earlier patch: http://git.qemu-project.org/?p=qemu.git;a=commit;h=913a87885f589d263e682c2eb6637c6e14538061 From 92f2b88cea48c6aeba8de568a45f2ed958f3c298 Mon Sep 17 00:00:00 2001 From: Gerd Hoffmann Date: Wed, 8 Feb 2017 11:18:36 +0100 Subject: [PATCH] cirrus: add blit_is_unsafe call to cirrus_bitblt_cputovideo (CVE-2017-2620) CIRRUS_BLTMODE_MEMSYSSRC blits do NOT check blit destination and blit width, at all. Oops. Fix it. Security impact: high. The missing blit destination check allows to write to host memory. Basically same as CVE-2014-8106 for the other blit variants. Cc: qemu-stable@nongnu.org Signed-off-by: Gerd Hoffmann --- hw/display/cirrus_vga.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c index 1deb52070a..b9e7cb1df1 100644 --- a/hw/display/cirrus_vga.c +++ b/hw/display/cirrus_vga.c @@ -900,6 +900,10 @@ static int cirrus_bitblt_cputovideo(CirrusVGAState * s) { int w; + if (blit_is_unsafe(s, true)) { + return 0; + } + s->cirrus_blt_mode &= ~CIRRUS_BLTMODE_MEMSYSSRC; s->cirrus_srcptr = &s->cirrus_bltbuf[0]; s->cirrus_srcptr_end = &s->cirrus_bltbuf[0]; @@ -925,6 +929,10 @@ static int cirrus_bitblt_cputovideo(CirrusVGAState * s) } s->cirrus_srccounter = s->cirrus_blt_srcpitch * s->cirrus_blt_height; } + + /* the blit_is_unsafe call above should catch this */ + assert(s->cirrus_blt_srcpitch <= CIRRUS_BLTBUFSIZE); + s->cirrus_srcptr = s->cirrus_bltbuf; s->cirrus_srcptr_end = s->cirrus_bltbuf + s->cirrus_blt_srcpitch; cirrus_update_memory_access(s); -- 2.12.0 From 913a87885f589d263e682c2eb6637c6e14538061 Mon Sep 17 00:00:00 2001 From: Bruce Rogers Date: Mon, 9 Jan 2017 13:35:20 -0700 Subject: [PATCH] display: cirrus: ignore source pitch value as needed in blit_is_unsafe Commit 4299b90 added a check which is too broad, given that the source pitch value is not required to be initialized for solid fill operations. This patch refines the blit_is_unsafe() check to ignore source pitch in that case. After applying the above commit as a security patch, we noticed the SLES 11 SP4 guest gui failed to initialize properly. Signed-off-by: Bruce Rogers Message-id: 20170109203520.5619-1-brogers@suse.com Signed-off-by: Gerd Hoffmann --- hw/display/cirrus_vga.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c index bdb092ee9d..379910db2d 100644 --- a/hw/display/cirrus_vga.c +++ b/hw/display/cirrus_vga.c @@ -294,7 +294,7 @@ static bool blit_region_is_unsafe(struct CirrusVGAState *s, return false; } -static bool blit_is_unsafe(struct CirrusVGAState *s) +static bool blit_is_unsafe(struct CirrusVGAState *s, bool dst_only) { /* should be the case, see cirrus_bitblt_start */ assert(s->cirrus_blt_width > 0); @@ -308,6 +308,9 @@ static bool blit_is_unsafe(struct CirrusVGAState *s) s->cirrus_blt_dstaddr & s->cirrus_addr_mask)) { return true; } + if (dst_only) { + return false; + } if (blit_region_is_unsafe(s, s->cirrus_blt_srcpitch, s->cirrus_blt_srcaddr & s->cirrus_addr_mask)) { return true; @@ -673,7 +676,7 @@ static int cirrus_bitblt_common_patterncopy(CirrusVGAState * s, dst = s->vga.vram_ptr + (s->cirrus_blt_dstaddr & s->cirrus_addr_mask); - if (blit_is_unsafe(s)) + if (blit_is_unsafe(s, false)) return 0; (*s->cirrus_rop) (s, dst, src, @@ -691,7 +694,7 @@ static int cirrus_bitblt_solidfill(CirrusVGAState *s, int blt_rop) { cirrus_fill_t rop_func; - if (blit_is_unsafe(s)) { + if (blit_is_unsafe(s, true)) { return 0; } rop_func = cirrus_fill[rop_to_index[blt_rop]][s->cirrus_blt_pixelwidth - 1]; @@ -795,7 +798,7 @@ static int cirrus_do_copy(CirrusVGAState *s, int dst, int src, int w, int h) static int cirrus_bitblt_videotovideo_copy(CirrusVGAState * s) { - if (blit_is_unsafe(s)) + if (blit_is_unsafe(s, false)) return 0; return cirrus_do_copy(s, s->cirrus_blt_dstaddr - s->vga.start_addr, -- 2.12.0