diff options
| author | Denis Efremov <efremov@ispras.ru> | 2019-07-12 21:55:23 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-07-31 07:28:34 +0200 |
| commit | 80637a906eded08e04ed8a6fbbdd2b8112eaa387 (patch) | |
| tree | 55a98edca9db9630c1cf793f1a78e343320ee9c6 /drivers/block/floppy.c | |
| parent | 4dae773077f3ff8f048df1357b098e23af91eb6d (diff) | |
floppy: fix out-of-bounds read in copy_buffer
[ Upstream commit da99466ac243f15fbba65bd261bfc75ffa1532b6 ]
This fixes a global out-of-bounds read access in the copy_buffer
function of the floppy driver.
The FDDEFPRM ioctl allows one to set the geometry of a disk. The sect
and head fields (unsigned int) of the floppy_drive structure are used to
compute the max_sector (int) in the make_raw_rw_request function. It is
possible to overflow the max_sector. Next, max_sector is passed to the
copy_buffer function and used in one of the memcpy calls.
An unprivileged user could trigger the bug if the device is accessible,
but requires a floppy disk to be inserted.
The patch adds the check for the .sect * .head multiplication for not
overflowing in the set_geometry function.
The bug was found by syzkaller.
Signed-off-by: Denis Efremov <efremov@ispras.ru>
Tested-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/block/floppy.c')
| -rw-r--r-- | drivers/block/floppy.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c index b4051e251041..a9d1430fc5ee 100644 --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -3239,8 +3239,10 @@ static int set_geometry(unsigned int cmd, struct floppy_struct *g, int cnt; /* sanity checking for parameters. */ - if (g->sect <= 0 || - g->head <= 0 || + if ((int)g->sect <= 0 || + (int)g->head <= 0 || + /* check for overflow in max_sector */ + (int)(g->sect * g->head) <= 0 || /* check for zero in F_SECT_PER_TRACK */ (unsigned char)((g->sect << 2) >> FD_SIZECODE(g)) == 0 || g->track <= 0 || g->track > UDP->tracks >> STRETCH(g) || |