6.6-stable review patch. If anyone has any objections, please let me know.
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From: Dan Carpenter dan.carpenter@linaro.org
commit e4185bed738da755b191aa3f2e16e8b48450e1b8 upstream.
The "req.start" and "req.len" variables are u64 values that come from the user at the start of the function. We mask away the high 32 bits of "req.len" so that's capped at U32_MAX but the "req.start" variable can go up to U64_MAX which means that the addition can still integer overflow.
Use check_add_overflow() to fix this bug.
Fixes: 095bb6e44eb1 ("mtdchar: add MEMREAD ioctl") Fixes: 6420ac0af95d ("mtdchar: prevent unbounded allocation in MEMWRITE ioctl") Cc: stable@vger.kernel.org Signed-off-by: Dan Carpenter dan.carpenter@linaro.org Signed-off-by: Miquel Raynal miquel.raynal@bootlin.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/mtd/mtdchar.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/drivers/mtd/mtdchar.c +++ b/drivers/mtd/mtdchar.c @@ -599,6 +599,7 @@ mtdchar_write_ioctl(struct mtd_info *mtd uint8_t *datbuf = NULL, *oobbuf = NULL; size_t datbuf_len, oobbuf_len; int ret = 0; + u64 end;
if (copy_from_user(&req, argp, sizeof(req))) return -EFAULT; @@ -618,7 +619,7 @@ mtdchar_write_ioctl(struct mtd_info *mtd req.len &= 0xffffffff; req.ooblen &= 0xffffffff;
- if (req.start + req.len > mtd->size) + if (check_add_overflow(req.start, req.len, &end) || end > mtd->size) return -EINVAL;
datbuf_len = min_t(size_t, req.len, mtd->erasesize); @@ -698,6 +699,7 @@ mtdchar_read_ioctl(struct mtd_info *mtd, size_t datbuf_len, oobbuf_len; size_t orig_len, orig_ooblen; int ret = 0; + u64 end;
if (copy_from_user(&req, argp, sizeof(req))) return -EFAULT; @@ -724,7 +726,7 @@ mtdchar_read_ioctl(struct mtd_info *mtd, req.len &= 0xffffffff; req.ooblen &= 0xffffffff;
- if (req.start + req.len > mtd->size) { + if (check_add_overflow(req.start, req.len, &end) || end > mtd->size) { ret = -EINVAL; goto out; }