FAILED: patch "[PATCH] zram: fix out-of-bounds access in read_block_state()" failed to apply to 5.15-stable tree

FAILED: patch "[PATCH] zram: fix out-of-bounds access in read_block_state()" failed to apply to 5.15-stable tree

[gregkh]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 391f057f44a51cc9418da5cba78b014324174264
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026090354-deafening-decorated-22e7@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 391f057f44a51cc9418da5cba78b014324174264 Mon Sep 17 00:00:00 2001
From: Longlong Xia <xialonglong@kylinos.cn>
Date: Tue, 4 Aug 2026 14:59:19 +0800
Subject: [PATCH] zram: fix out-of-bounds access in read_block_state()

read_block_state() calculates nr_pages before taking dev_lock.  If the
device is reset and reinitialized with a smaller disksize before lock
acquisition, nr_pages still describes the old table.  The subsequent loop
can then call slot_lock() past the end of the newly allocated table.

Read disksize after acquiring dev_lock and checking that the device is
initialized.  The read lock then keeps the table and its bound stable for
the duration of the scan.

Link: https://lore.kernel.org/20260804065919.3970386-3-xialonglong2025@163.com
Fixes: c0265342bff4 ("zram: introduce zram memory tracking")
Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Longlong Xia <xialonglong@kylinos.cn>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 2be5c20e3f14..82b78e6e55b2 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1543,7 +1543,7 @@ static ssize_t read_block_state(struct file *file, char __user *buf,
 	char *kbuf;
 	ssize_t index, written = 0;
 	struct zram *zram = file->private_data;
-	unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
+	unsigned long nr_pages;
 
 	kbuf = kvmalloc(count, GFP_KERNEL);
 	if (!kbuf)
@@ -1555,6 +1555,8 @@ static ssize_t read_block_state(struct file *file, char __user *buf,
 		return -EINVAL;
 	}
 
+	nr_pages = zram->disksize >> PAGE_SHIFT;
+
 	for (index = *ppos; index < nr_pages; index++) {
 		int copied;
 

[PATCH 5.15.y 1/2] zram: fixup read_block_state()

[Sasha Levin]

From: Sergey Senozhatsky <senozhatsky@chromium.org>

[ Upstream commit 8b05d2d8af817c6a1e23032df51e7ad83030d543 ]

ac_time is now in seconds, do not use ktime_to_timespec64()

[akpm@linux-foundation.org: remove now-unused local `ts']
[akpm@linux-foundation.org: fix build]
Link: https://lkml.kernel.org/r/20260115033031.3818977-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reported-by: Chris Mason <clm@meta.com>
Closes: https://lkml.kernel.org/r/20260114124522.1326519-1-clm@meta.com
Cc: Brian Geffon <bgeffon@google.com>
Cc: David Stevens <stevensd@google.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Richard Chang <richardycc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

[ Stable tree note: The ac_time conversion described above is not present
  here, so retain the ktime_t conversion and microsecond output.  Move the
  timespec64 temporary into the scan loop instead, allowing the follow-up
  bounds fix to move nr_pages initialization under init_lock cleanly. ]

Stable-dep-of: 391f057f44a5 ("zram: fix out-of-bounds access in read_block_state()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/block/zram/zram_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index a9f71b27d235a..d1f4b61509a0c 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -886,7 +886,6 @@ static ssize_t read_block_state(struct file *file, char __user *buf,
 	ssize_t index, written = 0;
 	struct zram *zram = file->private_data;
 	unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
-	struct timespec64 ts;
 
 	kbuf = kvmalloc(count, GFP_KERNEL);
 	if (!kbuf)
@@ -901,6 +900,7 @@ static ssize_t read_block_state(struct file *file, char __user *buf,
 
 	for (index = *ppos; index < nr_pages; index++) {
 		int copied;
+		struct timespec64 ts;
 
 		zram_slot_lock(zram, index);
 		if (!zram_allocated(zram, index))
-- 
2.53.0

[PATCH 5.15.y 2/2] zram: fix out-of-bounds access in read_block_state()

[Sasha Levin]

From: Longlong Xia <xialonglong@kylinos.cn>

[ Upstream commit 391f057f44a51cc9418da5cba78b014324174264 ]

read_block_state() calculates nr_pages before taking dev_lock.  If the
device is reset and reinitialized with a smaller disksize before lock
acquisition, nr_pages still describes the old table.  The subsequent loop
can then call slot_lock() past the end of the newly allocated table.

Read disksize after acquiring dev_lock and checking that the device is
initialized.  The read lock then keeps the table and its bound stable for
the duration of the scan.

Link: https://lore.kernel.org/20260804065919.3970386-3-xialonglong2025@163.com
Fixes: c0265342bff4 ("zram: introduce zram memory tracking")
Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Longlong Xia <xialonglong@kylinos.cn>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/block/zram/zram_drv.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index d1f4b61509a0c..5c44967b1c73f 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -885,7 +885,7 @@ static ssize_t read_block_state(struct file *file, char __user *buf,
 	char *kbuf;
 	ssize_t index, written = 0;
 	struct zram *zram = file->private_data;
-	unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
+	unsigned long nr_pages;
 
 	kbuf = kvmalloc(count, GFP_KERNEL);
 	if (!kbuf)
@@ -898,6 +898,8 @@ static ssize_t read_block_state(struct file *file, char __user *buf,
 		return -EINVAL;
 	}
 
+	nr_pages = zram->disksize >> PAGE_SHIFT;
+
 	for (index = *ppos; index < nr_pages; index++) {
 		int copied;
 		struct timespec64 ts;
-- 
2.53.0