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Re: [PATCH] 9pfs: Fix divide by zero bug
From: |
Christian Schoenebeck |
Subject: |
Re: [PATCH] 9pfs: Fix divide by zero bug |
Date: |
Fri, 22 Nov 2019 22:53:09 +0100 |
On Freitag, 22. November 2019 21:00:34 CET Dan Schatzberg wrote:
> Some filesystems may return 0s in statfs (trivially, a FUSE filesystem
> can do so). QEMU should handle this gracefully and just behave the
> same as if statfs failed.
Is that actually legal in non-error cases? Shouldn't a driver without a block
size concept return 512 according to POSIX?
> Signed-off-by: Dan Schatzberg <address@hidden>
> ---
> hw/9pfs/9p.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> index 37abcdb71e..520177f40c 100644
> --- a/hw/9pfs/9p.c
> +++ b/hw/9pfs/9p.c
> @@ -1834,8 +1834,10 @@ static int32_t coroutine_fn get_iounit(V9fsPDU *pdu,
> V9fsPath *path) * and as well as less than (client msize - P9_IOHDRSZ))
> */
> if (!v9fs_co_statfs(pdu, path, &stbuf)) {
> - iounit = stbuf.f_bsize;
> - iounit *= (s->msize - P9_IOHDRSZ)/stbuf.f_bsize;
> + if (stbuf.f_bsize) {
> + iounit = stbuf.f_bsize;
> + iounit *= (s->msize - P9_IOHDRSZ) / stbuf.f_bsize;
> + }
> }
> if (!iounit) {
> iounit = s->msize - P9_IOHDRSZ;
Nevertheless, since that will leave iounit initialized with zero and since
there is already an !ionunit case handling there ...
Acked-by: Christian Schoenebeck <address@hidden>
Best regards,
Christian Schoenebeck