diff options
| author | Denis Efremov <efremov@ispras.ru> | 2019-07-12 21:55:23 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-07-26 10:12:52 +0300 |
| commit | 0a67173bdf79bc7f45947b998a5beadff03bce00 (patch) | |
| tree | cf6803f06942f7bfa4da3078b379681df2712013 /drivers | |
| parent | deaa1395704c12ebea8c30a6da15b47ca3f88af5 (diff) | |
| download | linux-0a67173bdf79bc7f45947b998a5beadff03bce00.tar.xz | |
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')
| -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 8b443ee1d005..38e5811a045e 100644 --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -3232,8 +3232,10 @@ 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) || |