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Re: [Qemu-devel] [PATCH v2] 9pfs: fix integer overflow issue in xattr re
From: |
Greg Kurz |
Subject: |
Re: [Qemu-devel] [PATCH v2] 9pfs: fix integer overflow issue in xattr read/write |
Date: |
Thu, 13 Oct 2016 09:52:31 +0200 |
On Wed, 12 Oct 2016 19:53:39 -0700
Li Qiang <address@hidden> wrote:
> From: Li Qiang <address@hidden>
>
> In 9pfs xattr read/write function, it mix to use unsigned/signed
> ,32/64 bits integers. This will causes oob read/write issues. This patch
> fix this.
>
I suggested a more detailed changelog.
> Signed-off-by: Li Qiang <address@hidden>
> ---
> hw/9pfs/9p.c | 34 +++++++++++++---------------------
> hw/9pfs/9p.h | 4 ++--
> 2 files changed, 15 insertions(+), 23 deletions(-)
>
> diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> index e4040dc..8c7488f 100644
> --- a/hw/9pfs/9p.c
> +++ b/hw/9pfs/9p.c
> @@ -1642,20 +1642,17 @@ static int v9fs_xattr_read(V9fsState *s, V9fsPDU
> *pdu, V9fsFidState *fidp,
> {
> ssize_t err;
> size_t offset = 7;
> - int read_count;
> - int64_t xattr_len;
> + uint64_t read_count;
> V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
> VirtQueueElement *elem = v->elems[pdu->idx];
>
> - xattr_len = fidp->fs.xattr.len;
> - read_count = xattr_len - off;
> + if (fidp->fs.xattr.len < off) {
> + read_count = 0;
> + } else {
> + read_count = fidp->fs.xattr.len - off;
> + }
> if (read_count > max_count) {
> read_count = max_count;
> - } else if (read_count < 0) {
> - /*
> - * read beyond XATTR value
> - */
> - read_count = 0;
> }
> err = pdu_marshal(pdu, offset, "d", read_count);
> if (err < 0) {
> @@ -1982,23 +1979,18 @@ static int v9fs_xattr_write(V9fsState *s, V9fsPDU
> *pdu, V9fsFidState *fidp,
> {
> int i, to_copy;
> ssize_t err = 0;
> - int write_count;
> - int64_t xattr_len;
> + uint64_t write_count;
> size_t offset = 7;
>
>
> - xattr_len = fidp->fs.xattr.len;
> - write_count = xattr_len - off;
> - if (write_count > count) {
> - write_count = count;
> - } else if (write_count < 0) {
> - /*
> - * write beyond XATTR value len specified in
> - * xattrcreate
> - */
> + if (fidp->fs.xattr.len < off) {
> err = -ENOSPC;
> goto out;
> }
> + write_count = fidp->fs.xattr.len - off;
> + if (write_count > count) {
> + write_count = count;
> + }
> err = pdu_marshal(pdu, offset, "d", write_count);
> if (err < 0) {
> return err;
> @@ -3254,7 +3246,7 @@ static void v9fs_xattrcreate(void *opaque)
> {
> int flags;
> int32_t fid;
> - int64_t size;
> + uint64_t size;
> ssize_t err = 0;
> V9fsString name;
> size_t offset = 7;
> diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h
> index d539d2e..22198f6 100644
> --- a/hw/9pfs/9p.h
> +++ b/hw/9pfs/9p.h
> @@ -159,8 +159,8 @@ typedef struct V9fsConf
>
> typedef struct V9fsXattr
> {
> - int64_t copied_len;
> - int64_t len;
> + uint64_t copied_len;
> + uint64_t len;
I had asked this to go to a separate patch... with the appropriate
justifications that these are byte counts and size_t/u64 in the guest.
> void *value;
> V9fsString name;
> int flags;