[PATCH] NFSv4.2: Fix a potential double free with READ_PLUS
From: Anna Schumaker <anna@kernel.org>
Date: 2023-05-19 21:17:43
Subsystem:
filesystems (vfs and infrastructure), nfs, sunrpc, and lockd clients, the rest · Maintainers:
Alexander Viro, Christian Brauner, Trond Myklebust, Anna Schumaker, Linus Torvalds
From: Anna Schumaker <redacted> kfree()-ing the scratch page isn't enough, we also need to set the pointer back to NULL to avoid a double-free in the case of a resend. Fixes: fbd2a05f29a9 (NFSv4.2: Rework scratch handling for READ_PLUS) Signed-off-by: Anna Schumaker <redacted> --- fs/nfs/nfs4proc.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 18f25ff4bff7..d3665390c4cb 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c@@ -5437,10 +5437,18 @@ static bool nfs4_read_plus_not_supported(struct rpc_task *task, return false; } -static int nfs4_read_done(struct rpc_task *task, struct nfs_pgio_header *hdr) +static inline void nfs4_read_plus_scratch_free(struct nfs_pgio_header *hdr) { - if (hdr->res.scratch) + if (hdr->res.scratch) { kfree(hdr->res.scratch); + hdr->res.scratch = NULL; + } +} + +static int nfs4_read_done(struct rpc_task *task, struct nfs_pgio_header *hdr) +{ + nfs4_read_plus_scratch_free(hdr); + if (!nfs4_sequence_done(task, &hdr->res.seq_res)) return -EAGAIN; if (nfs4_read_stateid_changed(task, &hdr->args))
--
2.40.1