From: Eric Biggers <ebiggers@kernel.org>
To: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org,
Mimi Zohar <zohar@linux.vnet.ibm.com>,
Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Subject: Re: [PATCH] vfs: require i_size <= SIZE_MAX in kernel_read_file()
Date: Wed, 3 Oct 2018 16:43:35 -0700 [thread overview]
Message-ID: <20181003234334.GC58226@gmail.com> (raw)
In-Reply-To: <20180907191624.186623-1-ebiggers@kernel.org>
On Fri, Sep 07, 2018 at 12:16:24PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> On 32-bit systems, the buffer allocated by kernel_read_file() is too
> small if the file size is > SIZE_MAX, due to truncation to size_t.
>
> Fortunately, since the 'count' argument to kernel_read() is also
> truncated to size_t, only the allocated space is filled; then, -EIO is
> returned since 'pos != i_size' after the read loop.
>
> But this is not obvious and seems incidental. We should be more
> explicit about this case. So, fail early if i_size > SIZE_MAX.
>
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
> fs/exec.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fs/exec.c b/fs/exec.c
> index 1ebf6e5a521d..fc281b738a98 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -908,14 +908,14 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
> goto out;
>
> i_size = i_size_read(file_inode(file));
> - if (max_size > 0 && i_size > max_size) {
> - ret = -EFBIG;
> - goto out;
> - }
> if (i_size <= 0) {
> ret = -EINVAL;
> goto out;
> }
> + if (i_size > SIZE_MAX || (max_size > 0 && i_size > max_size)) {
> + ret = -EFBIG;
> + goto out;
> + }
>
> if (id != READING_FIRMWARE_PREALLOC_BUFFER)
> *buf = vmalloc(i_size);
> --
Al, are you planning to apply this?
- Eric
prev parent reply other threads:[~2018-10-04 6:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-07 19:16 [PATCH] vfs: require i_size <= SIZE_MAX in kernel_read_file() Eric Biggers
2018-09-21 18:42 ` Mimi Zohar
2018-10-03 23:43 ` Eric Biggers [this message]
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