From 136816bd2f82e3058fcbccedad3647d7acb42794 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Mon, 14 Dec 2020 13:37:46 -0800 Subject: [PATCH] Input: cyapa_gen6 - fix out-of-bounds stack access BugLink: https://bugs.launchpad.net/bugs/1910822 commit f051ae4f6c732c231046945b36234e977f8467c6 upstream. 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 Link: https://lore.kernel.org/r/20201026161332.3708389-1-arnd@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Dmitry Torokhov Signed-off-by: Greg Kroah-Hartman Signed-off-by: Kamal Mostafa Signed-off-by: Kelsey Skunberg --- drivers/input/mouse/cyapa_gen6.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/input/mouse/cyapa_gen6.c b/drivers/input/mouse/cyapa_gen6.c index c1b524ab4623..ba50f5713423 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); -- 2.39.5