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nfsd/nfsd3_proc_readdir: fix buffer count and page pointers

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After this commit
  f875a79 nfsd: allow nfsv3 readdir request to be larger.
nfsv3 readdir request size can be larger than PAGE_SIZE. So if the
directory been read is large enough, we can use multiple pages
in rq_respages. Update buffer count and page pointers like we do
in readdirplus to make this happen.

Now listing a directory within 3000 files will panic because we
are counting in a wrong way and would write on random page.

Fixes: f875a79 "nfsd: allow nfsv3 readdir request to be larger"
Signed-off-by: Murphy Zhou <jencce.kernel@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Murphy Zhou 2019-04-04 14:57:11 +08:00 committed by J. Bruce Fields
parent d58431eacb
commit 3c86794ac0
2 changed files with 24 additions and 4 deletions
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17
fs/nfsd/nfs3proc.c
View File

@ -442,7 +442,9 @@ nfsd3_proc_readdir(struct svc_rqst *rqstp)
struct nfsd3_readdirargs *argp = rqstp->rq_argp;
struct nfsd3_readdirres *resp = rqstp->rq_resp;
__be32 nfserr;
int count;
int count = 0;
struct page **p;
caddr_t page_addr = NULL;
dprintk("nfsd: READDIR(3) %s %d bytes at %d\n",
SVCFH_fmt(&argp->fh),
@ -462,7 +464,18 @@ nfsd3_proc_readdir(struct svc_rqst *rqstp)
nfserr = nfsd_readdir(rqstp, &resp->fh, (loff_t*) &argp->cookie,
&resp->common, nfs3svc_encode_entry);
memcpy(resp->verf, argp->verf, 8);
resp->count = resp->buffer - argp->buffer;
count = 0;
for (p = rqstp->rq_respages + 1; p < rqstp->rq_next_page; p++) {
page_addr = page_address(*p);
if (((caddr_t)resp->buffer >= page_addr) &&
((caddr_t)resp->buffer < page_addr + PAGE_SIZE)) {
count += (caddr_t)resp->buffer - page_addr;
break;
}
count += PAGE_SIZE;
}
resp->count = count >> 2;
if (resp->offset) {
loff_t offset = argp->cookie;

11
fs/nfsd/nfs3xdr.c
View File

@ -573,6 +573,7 @@ int
nfs3svc_decode_readdirargs(struct svc_rqst *rqstp, __be32 *p)
{
struct nfsd3_readdirargs *args = rqstp->rq_argp;
int len;
u32 max_blocksize = svc_max_payload(rqstp);
p = decode_fh(p, &args->fh);
@ -582,8 +583,14 @@ nfs3svc_decode_readdirargs(struct svc_rqst *rqstp, __be32 *p)
args->verf = p; p += 2;
args->dircount = ~0;
args->count = ntohl(*p++);
args->count = min_t(u32, args->count, max_blocksize);
args->buffer = page_address(*(rqstp->rq_next_page++));
len = args->count = min_t(u32, args->count, max_blocksize);
while (len > 0) {
struct page *p = *(rqstp->rq_next_page++);
if (!args->buffer)
args->buffer = page_address(p);
len -= PAGE_SIZE;
}
return xdr_argsize_check(rqstp, p);
}