On Mon, 13 Sept 2021 at 19:51, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > From: Baokun Li <libaokun1@xxxxxxxxxx> > > [ Upstream commit fad7cd3310db3099f95dd34312c77740fbc455e5 ] > > If user specify a large enough value of NBD blocks option, it may trigger > signed integer overflow which may lead to nbd->config->bytesize becomes a > large or small value, zero in particular. > > UBSAN: Undefined behaviour in drivers/block/nbd.c:325:31 > signed integer overflow: > 1024 * 4611686155866341414 cannot be represented in type 'long long int' > [...] > Call trace: > [...] > handle_overflow+0x188/0x1dc lib/ubsan.c:192 > __ubsan_handle_mul_overflow+0x34/0x44 lib/ubsan.c:213 > nbd_size_set drivers/block/nbd.c:325 [inline] > __nbd_ioctl drivers/block/nbd.c:1342 [inline] > nbd_ioctl+0x998/0xa10 drivers/block/nbd.c:1395 > __blkdev_driver_ioctl block/ioctl.c:311 [inline] > [...] > > Although it is not a big deal, still silence the UBSAN by limit > the input value. > > Reported-by: Hulk Robot <hulkci@xxxxxxxxxx> > Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx> > Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> > Link: https://lore.kernel.org/r/20210804021212.990223-1-libaokun1@xxxxxxxxxx > [axboe: dropped unlikely()] > Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > --- > drivers/block/nbd.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c > index 19f5d5a8b16a..acf3f85bf3c7 100644 > --- a/drivers/block/nbd.c > +++ b/drivers/block/nbd.c > @@ -1388,6 +1388,7 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, > unsigned int cmd, unsigned long arg) > { > struct nbd_config *config = nbd->config; > + loff_t bytesize; > > switch (cmd) { > case NBD_DISCONNECT: > @@ -1402,8 +1403,9 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, > case NBD_SET_SIZE: > return nbd_set_size(nbd, arg, config->blksize); > case NBD_SET_SIZE_BLOCKS: > - return nbd_set_size(nbd, arg * config->blksize, > - config->blksize); > + if (check_mul_overflow((loff_t)arg, config->blksize, &bytesize)) > + return -EINVAL; > + return nbd_set_size(nbd, bytesize, config->blksize); > case NBD_SET_TIMEOUT: > nbd_set_cmd_timeout(nbd, arg); > return 0; arm clang-10, clang-11, clang-12 and clang-13 builds failed. due to this commit on 5.14 and 5.13 on following configs, - footbridge_defconfig - mini2440_defconfig - s3c2410_defconfig This was already reported on the mailing list. ERROR: modpost: "__mulodi4" [drivers/block/nbd.ko] undefined! #1438 https://github.com/ClangBuiltLinux/linux/issues/1438 [PATCH 00/10] raise minimum GCC version to 5.1 https://lore.kernel.org/lkml/20210910234047.1019925-1-ndesaulniers@xxxxxxxxxx/ linux-next: build failure while building Linus' tree https://lore.kernel.org/all/20210909182525.372ee687@xxxxxxxxxxxxxxxx/ Full build log, https://gitlab.com/Linaro/lkft/mirrors/stable/linux-stable-rc/-/jobs/1585407346#L1111 -- Linaro LKFT https://lkft.linaro.org
