diff mbox series

input: cyapa_gen6: fix out-of-bounds stack access

Message ID 20201026161332.3708389-1-arnd@kernel.org
State New
Headers show
Series input: cyapa_gen6: fix out-of-bounds stack access | expand

Commit Message

Arnd Bergmann Oct. 26, 2020, 4:13 p.m. UTC 
From: Arnd Bergmann <arnd@arndb.de>

gcc -Warray-bounds warns about a serious bug in
cyapa_pip_retrieve_data_structure:

drivers/input/mouse/cyapa_gen6.c: In function 'cyapa_pip_retrieve_data_structure.constprop':
include/linux/unaligned/access_ok.h:40:17: warning: array subscript -1 is outside array bounds of 'struct retrieve_data_struct_cmd[1]' [-Warray-bounds]
   40 |  *((__le16 *)p) = cpu_to_le16(val);
drivers/input/mouse/cyapa_gen6.c:569:13: note: while referencing 'cmd'
  569 |  } __packed cmd;
      |             ^~~

Apparently the '-2' was added to the pointer instead of the value,
writing garbage into the stack next to this variable.

Fixes: c2c06c41f700 ("Input: cyapa - add gen6 device module support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/input/mouse/cyapa_gen6.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Dmitry Torokhov Dec. 14, 2020, 11 p.m. UTC | #1 
On Mon, Oct 26, 2020 at 05:13:29PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>

> 

> gcc -Warray-bounds warns about a serious bug in

> cyapa_pip_retrieve_data_structure:

> 

> drivers/input/mouse/cyapa_gen6.c: In function 'cyapa_pip_retrieve_data_structure.constprop':

> include/linux/unaligned/access_ok.h:40:17: warning: array subscript -1 is outside array bounds of 'struct retrieve_data_struct_cmd[1]' [-Warray-bounds]

>    40 |  *((__le16 *)p) = cpu_to_le16(val);

> drivers/input/mouse/cyapa_gen6.c:569:13: note: while referencing 'cmd'

>   569 |  } __packed cmd;

>       |             ^~~

> 

> Apparently the '-2' was added to the pointer instead of the value,

> writing garbage into the stack next to this variable.

> 

> Fixes: c2c06c41f700 ("Input: cyapa - add gen6 device module support")

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>


Applied, thank you.

-- 
Dmitry
diff mbox series

Patch

diff --git a/drivers/input/mouse/cyapa_gen6.c b/drivers/input/mouse/cyapa_gen6.c
index 7eba66fbef58..812edfced86e 100644
--- a/drivers/input/mouse/cyapa_gen6.c
+++ b/drivers/input/mouse/cyapa_gen6.c
@@ -573,7 +573,7 @@  static int cyapa_pip_retrieve_data_structure(struct cyapa *cyapa,
 
 	memset(&cmd, 0, sizeof(cmd));
 	put_unaligned_le16(PIP_OUTPUT_REPORT_ADDR, &cmd.head.addr);
-	put_unaligned_le16(sizeof(cmd), &cmd.head.length - 2);
+	put_unaligned_le16(sizeof(cmd) - 2, &cmd.head.length);
 	cmd.head.report_id = PIP_APP_CMD_REPORT_ID;
 	cmd.head.cmd_code = PIP_RETRIEVE_DATA_STRUCTURE;
 	put_unaligned_le16(read_offset, &cmd.read_offset);