mainline inclusion from mainline-v7.1-rc1 commit 116b6b7acdd82605ed530232cd7509d1b5282f5c category: bugfix bugzilla: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Commit 1e8e9913672a ("nfsd: fix heap overflow in NFSv4.0 LOCK replay cache") capped the replay cache copy at NFSD4_REPLAY_ISIZE to prevent a heap overflow, but set rp_buflen to zero when the encoded response exceeded the inline buffer. A retransmitted LOCK reaching the replay path then produced only a status code with no operation body, resulting in a malformed XDR response. When the encoded response exceeds the 112-byte inline rp_ibuf, a buffer is kmalloc'd to hold it. If the allocation fails, rp_buflen remains zero, preserving the behavior from the capped-copy fix. The buffer is freed when the stateowner is released or when a subsequent operation's response fits in the inline buffer. Fixes: 1e8e9913672a ("nfsd: fix heap overflow in NFSv4.0 LOCK replay cache") Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Conflicts: fs/nfsd/nfs4state.c fs/nfsd/nfs4xdr.c fs/nfsd/state.h Signed-off-by: Lai Zewei <laizewei3@huawei.com> --- fs/nfsd/nfs4state.c | 16 ++++++++++++++++ fs/nfsd/nfs4xdr.c | 23 ++++++++++++++++------- fs/nfsd/state.h | 12 +++++++----- 3 files changed, 39 insertions(+), 12 deletions(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 3ff2c23043b6..990b9da0c47f 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -1191,8 +1191,24 @@ release_all_access(struct nfs4_ol_stateid *stp) } } +/** + * nfs4_replay_free_cache - release dynamically allocated replay buffer + * @rp: replay cache to reset + * + * If @rp->rp_buf points to a kmalloc'd buffer, free it and reset + * rp_buf to the inline rp_ibuf. Always zeroes rp_buflen. + */ +void nfs4_replay_free_cache(struct nfs4_replay *rp) +{ + if (rp->rp_buf != rp->rp_ibuf) + kfree(rp->rp_buf); + rp->rp_buf = rp->rp_ibuf; + rp->rp_buflen = 0; +} + static inline void nfs4_free_stateowner(struct nfs4_stateowner *sop) { + nfs4_replay_free_cache(&sop->so_replay); kfree(sop->so_owner.data); sop->so_ops->so_free(sop); } diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index dab375230703..da9c23ac067f 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -4459,14 +4459,23 @@ nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op) int len = xdr->buf->len - post_err_offset; so->so_replay.rp_status = op->status; - if (len <= NFSD4_REPLAY_ISIZE) { - so->so_replay.rp_buflen = len; - read_bytes_from_xdr_buf(xdr->buf, - post_err_offset, - so->so_replay.rp_buf, len); - } else { - so->so_replay.rp_buflen = 0; + if (len > NFSD4_REPLAY_ISIZE) { + char *buf = kmalloc(len, GFP_KERNEL); + + nfs4_replay_free_cache(&so->so_replay); + if (buf) { + so->so_replay.rp_buf = buf; + } else { + /* rp_buflen already zeroed; skip caching */ + goto status; + } + } else if (so->so_replay.rp_buf != so->so_replay.rp_ibuf) { + nfs4_replay_free_cache(&so->so_replay); } + so->so_replay.rp_buflen = len; + read_bytes_from_xdr_buf(xdr->buf, + post_err_offset, + so->so_replay.rp_buf, len); } status: /* Note that op->status is already in network byte order: */ diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h index 4dc8d2fdce0b..c6e4ea41d93a 100644 --- a/fs/nfsd/state.h +++ b/fs/nfsd/state.h @@ -377,10 +377,10 @@ struct nfs4_client_reclaim { * ~32(deleg. ace) = 112 bytes * * Some responses can exceed this. A LOCK denial includes the conflicting - * lock owner, which can be up to 1024 bytes (NFS4_OPAQUE_LIMIT). Responses - * larger than REPLAY_ISIZE are not cached in rp_ibuf; only rp_status is - * saved. Enlarging this constant increases the size of every - * nfs4_stateowner. + * lock owner, which can be up to 1024 bytes (NFS4_OPAQUE_LIMIT). When a + * response exceeds REPLAY_ISIZE, a buffer is dynamically allocated. If + * that allocation fails, only rp_status is saved. Enlarging this constant + * increases the size of every nfs4_stateowner. */ #define NFSD4_REPLAY_ISIZE 112 @@ -392,12 +392,14 @@ struct nfs4_client_reclaim { struct nfs4_replay { __be32 rp_status; unsigned int rp_buflen; - char *rp_buf; + char *rp_buf; /* rp_ibuf or kmalloc'd */ struct knfsd_fh rp_openfh; struct mutex rp_mutex; char rp_ibuf[NFSD4_REPLAY_ISIZE]; }; +extern void nfs4_replay_free_cache(struct nfs4_replay *rp); + struct nfs4_stateowner; struct nfs4_stateowner_operations { -- 2.52.0