raw_cmd_copyout() is potentially copying uninitialized kernel stack memory
since it is initializing `cmd` by assignment, which may cause the compiler
to leave uninitialized holes in this structure. Fix it by using memcpy()
instead.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 2145e15e0557 ("floppy: don't write kernel-only members to FDRAWCMD ioctl output")
Suggested-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Peilin Ye <yepeilin.cs@xxxxxxxxx>
---
$ pahole -C "floppy_raw_cmd" drivers/block/floppy.o
struct floppy_raw_cmd {
unsigned int flags; /* 0 4 */
/* XXX 4 bytes hole, try to pack */
void * data; /* 8 8 */
char * kernel_data; /* 16 8 */
struct floppy_raw_cmd * next; /* 24 8 */
long int length; /* 32 8 */
long int phys_length; /* 40 8 */
int buffer_length; /* 48 4 */
unsigned char rate; /* 52 1 */
unsigned char cmd_count; /* 53 1 */
union {
struct {
unsigned char cmd[16]; /* 54 16 */
/* --- cacheline 1 boundary (64 bytes) was 6 bytes ago --- */
unsigned char reply_count; /* 70 1 */
unsigned char reply[16]; /* 71 16 */
}; /* 54 33 */
unsigned char fullcmd[33]; /* 54 33 */
}; /* 54 33 */
/* XXX 1 byte hole, try to pack */
/* --- cacheline 1 boundary (64 bytes) was 24 bytes ago --- */
int track; /* 88 4 */
int resultcode; /* 92 4 */
int reserved1; /* 96 4 */
int reserved2; /* 100 4 */
/* size: 104, cachelines: 2, members: 14 */
/* sum members: 99, holes: 2, sum holes: 5 */
/* last cacheline: 40 bytes */
};
drivers/block/floppy.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 09079aee8dc4..b8ea98f7a9cb 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3126,7 +3126,9 @@ static int raw_cmd_copyout(int cmd, void __user *param,
int ret;
while (ptr) {
- struct floppy_raw_cmd cmd = *ptr;
+ struct floppy_raw_cmd cmd;
+
+ memcpy(&cmd, ptr, sizeof(cmd));
cmd.next = NULL;
cmd.kernel_data = NULL;
ret = copy_to_user(param, &cmd, sizeof(cmd));
--
2.25.1
