[PATCH 5.4.y] NFSD: Fix NFSv3 SETATTR/CREATE's handling of large file sizes

[PATCH 5.4.y] NFSD: Fix NFSv3 SETATTR/CREATE's handling of large file sizes

[Larry Bassel]

From: Chuck Lever <chuck.lever@oracle.com>

[ Upstream commit a648fdeb7c0e17177a2280344d015dba3fbe3314 ]

iattr::ia_size is a loff_t, so these NFSv3 procedures must be
careful to deal with incoming client size values that are larger
than s64_max without corrupting the value.

Silently capping the value results in storing a different value
than the client passed in which is unexpected behavior, so remove
the min_t() check in decode_sattr3().

Note that RFC 1813 permits only the WRITE procedure to return
NFS3ERR_FBIG. We believe that NFSv3 reference implementations
also return NFS3ERR_FBIG when ia_size is too large.

Cc: stable@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
(cherry picked from commit a648fdeb7c0e17177a2280344d015dba3fbe3314)
[Larry: backport to 5.4.y. Minor conflict resolved due to missing commit 9cde9360d18d
NFSD: Update the SETATTR3args decoder to use struct xdr_stream]
Signed-off-by: Larry Bassel <larry.bassel@oracle.com>
---
 fs/nfsd/nfs3xdr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 03e8c45a52f3..25b6b4db0af2 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -122,7 +122,7 @@ decode_sattr3(__be32 *p, struct iattr *iap, struct user_namespace *userns)
 
 		iap->ia_valid |= ATTR_SIZE;
 		p = xdr_decode_hyper(p, &newsize);
-		iap->ia_size = min_t(u64, newsize, NFS_OFFSET_MAX);
+		iap->ia_size = newsize;
 	}
 	if ((tmp = ntohl(*p++)) == 1) {	/* set to server time */
 		iap->ia_valid |= ATTR_ATIME;
-- 
2.46.0

Re: [PATCH 5.4.y] NFSD: Fix NFSv3 SETATTR/CREATE's handling of large file sizes

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: a648fdeb7c0e17177a2280344d015dba3fbe3314

WARNING: Author mismatch between patch and upstream commit:
Backport author: Larry Bassel<larry.bassel@oracle.com>
Commit author: Chuck Lever<chuck.lever@oracle.com>

Status in newer kernel trees:
6.15.y | Present (exact SHA1)
6.14.y | Present (exact SHA1)
6.12.y | Present (exact SHA1)
6.6.y | Present (exact SHA1)
6.1.y | Present (exact SHA1)
5.15.y | Present (different SHA1: 37f2d2cd8ead)
5.10.y | Present (different SHA1: a231ae6bb50e)

Note: The patch differs from the upstream commit:
---
1:  a648fdeb7c0e1 < -:  ------------- NFSD: Fix NFSv3 SETATTR/CREATE's handling of large file sizes
-:  ------------- > 1:  4ef4f5c0a5841 NFSD: Fix NFSv3 SETATTR/CREATE's handling of large file sizes
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.4.y        |  Success    |  Success   |