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display: cirrus: check vga bits per pixel(bpp) value 

In Cirrus CLGD 54xx VGA Emulator, if cirrus graphics mode is VGA,
'cirrus_get_bpp' returns zero(0), which could lead to a divide
by zero error in while copying pixel data. The same could occur
via blit pitch values. Add check to avoid it.

Reported-by: Huawei PSIRT <psirt@huawei.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-id: 1476776717-24807-1-git-send-email-ppandit@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
stable-2.8
Prasad J Pandit 2016-10-18 13:15:17 +05:30 committed by Gerd Hoffmann
parent 2d1cd6c7a9
commit 4299b90e9b
1 changed files with 10 additions and 4 deletions
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14
hw/display/cirrus_vga.c
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@ -272,6 +272,9 @@ static void cirrus_update_memory_access(CirrusVGAState *s);
static bool blit_region_is_unsafe(struct CirrusVGAState *s,
int32_t pitch, int32_t addr)
{
if (!pitch) {
return true;
}
if (pitch < 0) {
int64_t min = addr
+ ((int64_t)s->cirrus_blt_height-1) * pitch;
@ -715,7 +718,7 @@ static int cirrus_bitblt_videotovideo_patterncopy(CirrusVGAState * s)
s->cirrus_addr_mask));
}
static void cirrus_do_copy(CirrusVGAState *s, int dst, int src, int w, int h)
static int cirrus_do_copy(CirrusVGAState *s, int dst, int src, int w, int h)
{
int sx = 0, sy = 0;
int dx = 0, dy = 0;
@ -729,6 +732,9 @@ static void cirrus_do_copy(CirrusVGAState *s, int dst, int src, int w, int h)
int width, height;
depth = s->vga.get_bpp(&s->vga) / 8;
if (!depth) {
return 0;
}
s->vga.get_resolution(&s->vga, &width, &height);
/* extra x, y */
@ -783,6 +789,8 @@ static void cirrus_do_copy(CirrusVGAState *s, int dst, int src, int w, int h)
cirrus_invalidate_region(s, s->cirrus_blt_dstaddr,
s->cirrus_blt_dstpitch, s->cirrus_blt_width,
s->cirrus_blt_height);
return 1;
}
static int cirrus_bitblt_videotovideo_copy(CirrusVGAState * s)
@ -790,11 +798,9 @@ static int cirrus_bitblt_videotovideo_copy(CirrusVGAState * s)
if (blit_is_unsafe(s))
return 0;
cirrus_do_copy(s, s->cirrus_blt_dstaddr - s->vga.start_addr,
return cirrus_do_copy(s, s->cirrus_blt_dstaddr - s->vga.start_addr,
s->cirrus_blt_srcaddr - s->vga.start_addr,
s->cirrus_blt_width, s->cirrus_blt_height);
return 1;
}
/***************************************