6.12-stable review patch. If anyone has any objections, please let me know.
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From: Alex Markuze amarkuze@redhat.com
commit 9abee475803fab6ad59d4f4fc59c6a75374a7d9d upstream.
This patch refines the read logic in __ceph_sync_read() to ensure more predictable and efficient behavior in various edge cases.
- Return early if the requested read length is zero or if the file size (`i_size`) is zero. - Initialize the index variable (`idx`) where needed and reorder some code to ensure it is always set before use. - Improve error handling by checking for negative return values earlier. - Remove redundant encrypted file checks after failures. Only attempt filesystem-level decryption if the read succeeded. - Simplify leftover calculations to correctly handle cases where the read extends beyond the end of the file or stops short. This can be hit by continuously reading a file while, on another client, we keep truncating and writing new data into it. - This resolves multiple issues caused by integer and consequent buffer overflow (`pages` array being accessed beyond `num_pages`): - https://tracker.ceph.com/issues/67524 - https://tracker.ceph.com/issues/68980 - https://tracker.ceph.com/issues/68981
Cc: stable@vger.kernel.org Fixes: 1065da21e5df ("ceph: stop copying to iter at EOF on sync reads") Reported-by: Luis Henriques (SUSE) luis.henriques@linux.dev Signed-off-by: Alex Markuze amarkuze@redhat.com Reviewed-by: Viacheslav Dubeyko Slava.Dubeyko@ibm.com Signed-off-by: Ilya Dryomov idryomov@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ceph/file.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-)
--- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -1066,7 +1066,7 @@ ssize_t __ceph_sync_read(struct inode *i if (ceph_inode_is_shutdown(inode)) return -EIO;
- if (!len) + if (!len || !i_size) return 0; /* * flush any page cache pages in this range. this @@ -1086,7 +1086,7 @@ ssize_t __ceph_sync_read(struct inode *i int num_pages; size_t page_off; bool more; - int idx; + int idx = 0; size_t left; struct ceph_osd_req_op *op; u64 read_off = off; @@ -1160,7 +1160,14 @@ ssize_t __ceph_sync_read(struct inode *i else if (ret == -ENOENT) ret = 0;
- if (ret > 0 && IS_ENCRYPTED(inode)) { + if (ret < 0) { + ceph_osdc_put_request(req); + if (ret == -EBLOCKLISTED) + fsc->blocklisted = true; + break; + } + + if (IS_ENCRYPTED(inode)) { int fret;
fret = ceph_fscrypt_decrypt_extents(inode, pages, @@ -1189,7 +1196,7 @@ ssize_t __ceph_sync_read(struct inode *i ceph_osdc_put_request(req);
/* Short read but not EOF? Zero out the remainder. */ - if (ret >= 0 && ret < len && (off + ret < i_size)) { + if (ret < len && (off + ret < i_size)) { int zlen = min(len - ret, i_size - off - ret); int zoff = page_off + ret;
@@ -1199,13 +1206,11 @@ ssize_t __ceph_sync_read(struct inode *i ret += zlen; }
- idx = 0; - if (ret <= 0) - left = 0; - else if (off + ret > i_size) - left = i_size - off; + if (off + ret > i_size) + left = (i_size > off) ? i_size - off : 0; else left = ret; + while (left > 0) { size_t plen, copied;
@@ -1223,12 +1228,6 @@ ssize_t __ceph_sync_read(struct inode *i } ceph_release_page_vector(pages, num_pages);
- if (ret < 0) { - if (ret == -EBLOCKLISTED) - fsc->blocklisted = true; - break; - } - if (off >= i_size || !more) break; }