[Qemu-devel] [PATCH v2] vnc: fix unalignment access in tight_pack24

Li Qiang posted 1 patch 5 years, 1 month ago
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git fetch https://github.com/patchew-project/qemu tags/patchew/20190318010442.14897-1-liq3ea@163.com
Maintainers: Gerd Hoffmann <kraxel@redhat.com>
ui/vnc-enc-tight.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
[Qemu-devel] [PATCH v2] vnc: fix unalignment access in tight_pack24
Posted by Li Qiang 5 years, 1 month ago
When adding '-fsanitize=undefined' in compiling configuration
and connect VM with vnc, it reports following error:

ui/vnc-enc-tight.c:910:13: runtime error: load of
misaligned address 0x621000466513 for type 'uint32_t',
which requires 4 byte alignment

This patch fix this issue.

Signed-off-by: Li Qiang <liq3ea@163.com>
---
v1->v2: Use ldl_he_p per Peter's advice

 ui/vnc-enc-tight.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/ui/vnc-enc-tight.c b/ui/vnc-enc-tight.c
index 0b4a5ac71f..d20cd1d86d 100644
--- a/ui/vnc-enc-tight.c
+++ b/ui/vnc-enc-tight.c
@@ -886,11 +886,11 @@ static int tight_compress_data(VncState *vs, int stream_id, size_t bytes,
  */
 static void tight_pack24(VncState *vs, uint8_t *buf, size_t count, size_t *ret)
 {
-    uint32_t *buf32;
+    uint8_t *buf8;
     uint32_t pix;
     int rshift, gshift, bshift;
 
-    buf32 = (uint32_t *)buf;
+    buf8 = buf;
 
     if (1 /* FIXME */) {
         rshift = vs->client_pf.rshift;
@@ -907,10 +907,11 @@ static void tight_pack24(VncState *vs, uint8_t *buf, size_t count, size_t *ret)
     }
 
     while (count--) {
-        pix = *buf32++;
+        pix = ldl_he_p(buf8);
         *buf++ = (char)(pix >> rshift);
         *buf++ = (char)(pix >> gshift);
         *buf++ = (char)(pix >> bshift);
+        buf8 += 4;
     }
 }
 
-- 
2.17.1



Re: [Qemu-devel] [PATCH v2] vnc: fix unalignment access in tight_pack24
Posted by Gerd Hoffmann 5 years, 1 month ago
On Mon, Mar 18, 2019 at 09:04:42AM +0800, Li Qiang wrote:
> When adding '-fsanitize=undefined' in compiling configuration
> and connect VM with vnc, it reports following error:
> 
> ui/vnc-enc-tight.c:910:13: runtime error: load of
> misaligned address 0x621000466513 for type 'uint32_t',
> which requires 4 byte alignment
> 
> This patch fix this issue.

Added to ui patch queue.

thanks,
  Gerd