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Thu, 17 Sep 2026 01:38:50 -0700 (PDT) From: zjamg To: Song Liu , Yu Kuai Cc: Li Nan , Xiao Ni , NeilBrown , linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, zjamg , stable@vger.kernel.org Subject: [PATCH 1/2] md: fix bblog_size-driven OOB read in super_1_load() and super_1_sync() Date: Thu, 17 Sep 2026 16:38:19 +0800 Message-ID: <20260917083820.57091-2-ndaugoing@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260917083820.57091-1-ndaugoing@gmail.com> References: <20260917083820.57091-1-ndaugoing@gmail.com> Precedence: bulk X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In super_1_load(), when the on-disk feature_map does not have the MD_FEATURE_BAD_BLOCKS flag set, but sb->bblog_offset is non-zero, rdev->badblocks.shift is initialized to 0 while completely bypassing the sectors > (PAGE_SIZE / 512) validation check on sb->bblog_size. Subsequently, when badblocks are updated, super_1_sync() enables the MD_FEATURE_BAD_BLOCKS feature flag and assigns bb->size directly from sb->bblog_size without validating that bb->size fits within the single allocated rdev->bb_page (which is PAGE_SIZE, or PAGE_SIZE / 512 sectors). When md_update_sb() later writes metadata via md_write_metadata(), an unvalidated bb->size (e.g. 0xFFFF) results in a bio whose length exceeds the backing page, causing out-of-bounds reads into kernel memory during block I/O and leaking kernel slab/page contents to disk. Fix this by: 1. Validating sb->bblog_size in the 'else if (sb->bblog_offset != 0)' branch of super_1_load(), returning -EINVAL on oversized values. 2. Clamping bb->size in super_1_sync() to PAGE_SIZE / 512 to ensure it never exceeds the backing rdev->bb_page capacity. Fixes: 2699b67223ac ("md: load/store badblock list from v1.x metadata") Cc: stable@vger.kernel.org Signed-off-by: zjamg --- drivers/md/md.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 680b34a63cb3..d2433cf41e65 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -1934,8 +1934,11 @@ static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_ if (!badblocks_set(&rdev->badblocks, sector, count, 1)) return -EINVAL; } - } else if (sb->bblog_offset != 0) + } else if (sb->bblog_offset != 0) { + if (le16_to_cpu(sb->bblog_size) > (PAGE_SIZE / 512)) + return -EINVAL; rdev->badblocks.shift = 0; + } if ((le32_to_cpu(sb->feature_map) & (MD_FEATURE_PPL | MD_FEATURE_MULTIPLE_PPLS))) { @@ -2313,7 +2316,8 @@ static void super_1_sync(struct mddev *mddev, struct md_rdev *rdev) bb->sector = (rdev->sb_start + (int)le32_to_cpu(sb->bblog_offset)); - bb->size = le16_to_cpu(sb->bblog_size); + bb->size = min_t(sector_t, le16_to_cpu(sb->bblog_size), + PAGE_SIZE / 512); } } -- 2.53.0