diff mbox series

ceph: fix overflowed value issue in ceph_submit_write()

Message ID 20250604224106.396310-1-slava@dubeyko.com
State New
Headers show
Series ceph: fix overflowed value issue in ceph_submit_write() | expand

Commit Message

Viacheslav Dubeyko June 4, 2025, 10:41 p.m. UTC 
From: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>

The Coverity Scan service has detected overflowed value
issue in ceph_submit_write() [1]. The CID 1646339 defect
contains explanation: "The overflowed value due to
arithmetic on constants is too small or unexpectedly
negative, causing incorrect computations.
In ceph_submit_write: Integer overflow occurs in
arithmetic on constant operands (CWE-190)".

This patch adds a check ceph_wbc->locked_pages on
equality to zero and it exits function if it has
zero value. Also, it introduces a processed_pages
variable with the goal of assigning the number of
processed pages and checking this number on
equality to zero. The check of processed_pages
variable on equality to zero should protect from
overflowed value of index that selects page in
ceph_wbc->pages[index] array.

[1] https://scan5.scan.coverity.com/#/project-view/64304/10063?selectedIssue=1646339

Signed-off-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
---
 fs/ceph/addr.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)
diff mbox series

Patch

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index b95c4cb21c13..afbb7aba283e 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -1411,6 +1411,7 @@  int ceph_submit_write(struct address_space *mapping,
 	bool caching = ceph_is_cache_enabled(inode);
 	u64 offset;
 	u64 len;
+	unsigned processed_pages;
 	unsigned i;
 
 new_request:
@@ -1438,6 +1439,9 @@  int ceph_submit_write(struct address_space *mapping,
 		BUG_ON(IS_ERR(req));
 	}
 
+	if (ceph_wbc->locked_pages == 0)
+		return -EINVAL;
+
 	page = ceph_wbc->pages[ceph_wbc->locked_pages - 1];
 	BUG_ON(len < ceph_fscrypt_page_offset(page) + thp_size(page) - offset);
 
@@ -1474,6 +1478,7 @@  int ceph_submit_write(struct address_space *mapping,
 	len = 0;
 	ceph_wbc->data_pages = ceph_wbc->pages;
 	ceph_wbc->op_idx = 0;
+	processed_pages = 0;
 	for (i = 0; i < ceph_wbc->locked_pages; i++) {
 		u64 cur_offset;
 
@@ -1517,19 +1522,22 @@  int ceph_submit_write(struct address_space *mapping,
 			ceph_set_page_fscache(page);
 
 		len += thp_size(page);
+		processed_pages++;
 	}
 
 	ceph_fscache_write_to_cache(inode, offset, len, caching);
 
 	if (ceph_wbc->size_stable) {
 		len = min(len, ceph_wbc->i_size - offset);
-	} else if (i == ceph_wbc->locked_pages) {
+	} else if (processed_pages > 0 &&
+		   processed_pages == ceph_wbc->locked_pages) {
 		/* writepages_finish() clears writeback pages
 		 * according to the data length, so make sure
 		 * data length covers all locked pages */
 		u64 min_len = len + 1 - thp_size(page);
+		unsigned index = processed_pages - 1;
 		len = get_writepages_data_length(inode,
-						 ceph_wbc->pages[i - 1],
+						 ceph_wbc->pages[index],
 						 offset);
 		len = max(len, min_len);
 	}
@@ -1554,17 +1562,17 @@  int ceph_submit_write(struct address_space *mapping,
 	BUG_ON(ceph_wbc->op_idx + 1 != req->r_num_ops);
 
 	ceph_wbc->from_pool = false;
-	if (i < ceph_wbc->locked_pages) {
+	if (processed_pages < ceph_wbc->locked_pages) {
 		BUG_ON(ceph_wbc->num_ops <= req->r_num_ops);
 		ceph_wbc->num_ops -= req->r_num_ops;
-		ceph_wbc->locked_pages -= i;
+		ceph_wbc->locked_pages -= processed_pages;
 
 		/* allocate new pages array for next request */
 		ceph_wbc->data_pages = ceph_wbc->pages;
 		__ceph_allocate_page_array(ceph_wbc, ceph_wbc->locked_pages);
-		memcpy(ceph_wbc->pages, ceph_wbc->data_pages + i,
+		memcpy(ceph_wbc->pages, ceph_wbc->data_pages + processed_pages,
 			ceph_wbc->locked_pages * sizeof(*ceph_wbc->pages));
-		memset(ceph_wbc->data_pages + i, 0,
+		memset(ceph_wbc->data_pages + processed_pages, 0,
 			ceph_wbc->locked_pages * sizeof(*ceph_wbc->pages));
 	} else {
 		BUG_ON(ceph_wbc->num_ops != req->r_num_ops);
@@ -1576,7 +1584,7 @@  int ceph_submit_write(struct address_space *mapping,
 	ceph_osdc_start_request(&fsc->client->osdc, req);
 	req = NULL;
 
-	wbc->nr_to_write -= i;
+	wbc->nr_to_write -= processed_pages;
 	if (ceph_wbc->pages)
 		goto new_request;