linux-kernel - [PATCH 1/1] md/md-bitmap: fix GPF in bitmap_get

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <20250702091035.2061312-1-haakon.bugge@oracle.com>
Date: Wed,  2 Jul 2025 11:10:34 +0200
From: Håkon Bugge <haakon.bugge@...cle.com>
To: Song Liu <song@...nel.org>, Yu Kuai <yukuai3@...wei.com>,
        Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>,
        Mel Gorman <mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>,
        Zheng Qixing <zhengqixing@...wei.com>
Cc: stable@...r.kernel.org, Gerald Gibson <gerald.gibson@...cle.com>,
        Håkon Bugge <haakon.bugge@...cle.com>,
        linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] md/md-bitmap: fix GPF in bitmap_get_stats()

The commit message of commit 6ec1f0239485 ("md/md-bitmap: fix stats
collection for external bitmaps") states:

    Remove the external bitmap check as the statistics should be
    available regardless of bitmap storage location.

    Return -EINVAL only for invalid bitmap with no storage (neither in
    superblock nor in external file).

But, the code does not adhere to the above, as it does only check for
a valid super-block for "internal" bitmaps. Hence, we observe:

Oops: GPF, probably for non-canonical address 0x1cd66f1f40000028
RIP: 0010:bitmap_get_stats+0x45/0xd0
Call Trace:

 seq_read_iter+0x2b9/0x46a
 seq_read+0x12f/0x180
 proc_reg_read+0x57/0xb0
 vfs_read+0xf6/0x380
 ksys_read+0x6d/0xf0
 do_syscall_64+0x8c/0x1b0
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

We fix this by checking the existence of a super-block for both the
internal and external case.

Fixes: 6ec1f0239485 ("md/md-bitmap: fix stats collection for external bitmaps")
Cc: stable@...r.kernel.org
Reported-by: Gerald Gibson <gerald.gibson@...cle.com>
Signed-off-by: Håkon Bugge <haakon.bugge@...cle.com>
---
 drivers/md/md-bitmap.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index bd694910b01b0..7f524a26cebca 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -2366,8 +2366,7 @@ static int bitmap_get_stats(void *data, struct md_bitmap_stats *stats)
 
 	if (!bitmap)
 		return -ENOENT;
-	if (!bitmap->mddev->bitmap_info.external &&
-	    !bitmap->storage.sb_page)
+	if (!bitmap->storage.sb_page)
 		return -EINVAL;
 	sb = kmap_local_page(bitmap->storage.sb_page);
 	stats->sync_size = le64_to_cpu(sb->sync_size);
-- 
2.43.5