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| author | Trond Myklebust <Trond.Myklebust@netapp.com> | 2012-08-26 22:44:43 +0400 |
|---|---|---|
| committer | Trond Myklebust <Trond.Myklebust@netapp.com> | 2012-09-06 19:11:53 +0400 |
| commit | 1f1ea6c2d9d8c0be9ec56454b05315273b5de8ce (patch) | |
| tree | 4718cdc2e494f18ab13c2c8f09930953b77c31ff /fs/nfs/nfs4proc.c | |
| parent | 21f498c2f73bd6150d82931f09965826dca0b5f2 (diff) | |
| download | linux-1f1ea6c2d9d8c0be9ec56454b05315273b5de8ce.tar.xz | |
NFSv4: Fix buffer overflow checking in __nfs4_get_acl_uncached
Pass the checks made by decode_getacl back to __nfs4_get_acl_uncached
so that it knows if the acl has been truncated.
The current overflow checking is broken, resulting in Oopses on
user-triggered nfs4_getfacl calls, and is opaque to the point
where several attempts at fixing it have failed.
This patch tries to clean up the code in addition to fixing the
Oopses by ensuring that the overflow checks are performed in
a single place (decode_getacl). If the overflow check failed,
we will still be able to report the acl length, but at least
we will no longer attempt to cache the acl or copy the
truncated contents to user space.
Reported-by: Sachin Prabhu <sprabhu@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Tested-by: Sachin Prabhu <sprabhu@redhat.com>
Diffstat (limited to 'fs/nfs/nfs4proc.c')
| -rw-r--r-- | fs/nfs/nfs4proc.c | 31 |
1 files changed, 12 insertions, 19 deletions
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 6b94f2d52532..1e50326d00dd 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -3739,7 +3739,7 @@ static void nfs4_write_cached_acl(struct inode *inode, struct page **pages, size struct nfs4_cached_acl *acl; size_t buflen = sizeof(*acl) + acl_len; - if (pages && buflen <= PAGE_SIZE) { + if (buflen <= PAGE_SIZE) { acl = kmalloc(buflen, GFP_KERNEL); if (acl == NULL) goto out; @@ -3784,7 +3784,6 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu }; unsigned int npages = DIV_ROUND_UP(buflen, PAGE_SIZE); int ret = -ENOMEM, i; - size_t acl_len = 0; /* As long as we're doing a round trip to the server anyway, * let's be prepared for a page of acl data. */ @@ -3807,11 +3806,6 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu args.acl_len = npages * PAGE_SIZE; args.acl_pgbase = 0; - /* Let decode_getfacl know not to fail if the ACL data is larger than - * the page we send as a guess */ - if (buf == NULL) - res.acl_flags |= NFS4_ACL_LEN_REQUEST; - dprintk("%s buf %p buflen %zu npages %d args.acl_len %zu\n", __func__, buf, buflen, npages, args.acl_len); ret = nfs4_call_sync(NFS_SERVER(inode)->client, NFS_SERVER(inode), @@ -3819,20 +3813,19 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu if (ret) goto out_free; - acl_len = res.acl_len; - if (acl_len > args.acl_len) - nfs4_write_cached_acl(inode, NULL, 0, acl_len); - else - nfs4_write_cached_acl(inode, pages, res.acl_data_offset, - acl_len); - if (buf) { + /* Handle the case where the passed-in buffer is too short */ + if (res.acl_flags & NFS4_ACL_TRUNC) { + /* Did the user only issue a request for the acl length? */ + if (buf == NULL) + goto out_ok; ret = -ERANGE; - if (acl_len > buflen) - goto out_free; - _copy_from_pages(buf, pages, res.acl_data_offset, - acl_len); + goto out_free; } - ret = acl_len; + nfs4_write_cached_acl(inode, pages, res.acl_data_offset, res.acl_len); + if (buf) + _copy_from_pages(buf, pages, res.acl_data_offset, res.acl_len); +out_ok: + ret = res.acl_len; out_free: for (i = 0; i < npages; i++) if (pages[i]) |