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* [f2fs-dev] [PATCH v2] f2fs: fix null page reference in redirty_blocks
@ 2021-01-05  4:16 Daeho Jeong
  2021-01-05  6:05 ` Chao Yu
                   ` (2 more replies)
  0 siblings, 3 replies; 8+ messages in thread
From: Daeho Jeong @ 2021-01-05  4:16 UTC (permalink / raw)
  To: linux-kernel, linux-f2fs-devel, kernel-team; +Cc: Colin Ian King, Daeho Jeong

From: Daeho Jeong <daehojeong@google.com>

Fixed null page reference when find_lock_page() fails in
redirty_blocks().

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reported-by: Colin Ian King <colin.king@canonical.com>
Fixes: 5fdb322ff2c2 ("f2fs: add F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE")
---
v2: changed error value and break the loop when error occurs
---
 fs/f2fs/file.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 9e5275716be8..d27173c24391 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -4060,8 +4060,10 @@ static int redirty_blocks(struct inode *inode, pgoff_t page_idx, int len)
 
 	for (i = 0; i < page_len; i++, redirty_idx++) {
 		page = find_lock_page(mapping, redirty_idx);
-		if (!page)
-			ret = -ENOENT;
+		if (!page) {
+			ret = -ENOMEM;
+			break;
+		}
 		set_page_dirty(page);
 		f2fs_put_page(page, 1);
 		f2fs_put_page(page, 0);
-- 
2.29.2.729.g45daf8777d-goog



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^ permalink raw reply related	[flat|nested] 8+ messages in thread
* [f2fs-dev] [PATCH v2] f2fs: fix null page reference in redirty_blocks
@ 2021-01-05 23:49 Daeho Jeong
  0 siblings, 0 replies; 8+ messages in thread
From: Daeho Jeong @ 2021-01-05 23:49 UTC (permalink / raw)
  To: linux-kernel, linux-f2fs-devel, kernel-team; +Cc: Colin Ian King, Daeho Jeong

From: Daeho Jeong <daehojeong@google.com>

By Colin's static analysis, we found out there is a null page reference
under low memory situation in redirty_blocks. I've made the page finding
loop stop immediately and return an error not to cause further memory
pressure when we run into a failure to find a page under low memory
condition.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reported-by: Colin Ian King <colin.king@canonical.com>
Fixes: 5fdb322ff2c2 ("f2fs: add F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE")
---
v2: changed error value and quit the page finding loop immediately
    when error occurs
---
 fs/f2fs/file.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 9e5275716be8..d27173c24391 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -4060,8 +4060,10 @@ static int redirty_blocks(struct inode *inode, pgoff_t page_idx, int len)
 
 	for (i = 0; i < page_len; i++, redirty_idx++) {
 		page = find_lock_page(mapping, redirty_idx);
-		if (!page)
-			ret = -ENOENT;
+		if (!page) {
+			ret = -ENOMEM;
+			break;
+		}
 		set_page_dirty(page);
 		f2fs_put_page(page, 1);
 		f2fs_put_page(page, 0);
-- 
2.29.2.729.g45daf8777d-goog



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^ permalink raw reply related	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2021-01-06  3:36 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2021-01-05  4:16 [f2fs-dev] [PATCH v2] f2fs: fix null page reference in redirty_blocks Daeho Jeong
2021-01-05  6:05 ` Chao Yu
2021-01-05  9:34 ` Colin Ian King
2021-01-05 12:04 ` Markus Elfring
2021-01-05 23:44   ` Daeho Jeong
2021-01-06  1:03   ` Chao Yu
2021-01-06  3:35     ` Daeho Jeong
  -- strict thread matches above, loose matches on Subject: below --
2021-01-05 23:49 Daeho Jeong

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