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Thu, 06 Mar 2025 05:29:34 -0800 (PST) From: Zhiyu Zhang To: phillip@squashfs.org.uk, akpm@linux-foundation.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Zhiyu Zhang Subject: [PATCH] squashfs: Fix invalid pointer dereference in squashfs_cache_delete Date: Thu, 6 Mar 2025 21:28:55 +0800 Message-Id: <20250306132855.2030-1-zhiyuzhang999@gmail.com> X-Mailer: git-send-email 2.39.1.windows.1 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 When mounting a squashfs fails, squashfs_cache_init() may return an error pointer (e.g., -ENOMEM) instead of NULL. However, squashfs_cache_delete() only checks for a NULL cache, and attempts to dereference the invalid pointer. This leads to a kernel crash (BUG: unable to handle kernel paging request in squashfs_cache_delete). This patch fixes the issue by checking IS_ERR(cache) before accessing it. Fixes: 49ff29240ebb ("squashfs: make squashfs_cache_init() return ERR_PTR(-ENOMEM)") Reported-by: Zhiyu Zhang Closes: https://lore.kernel.org/linux-fsdevel/CALf2hKvaq8B4u5yfrE+BYt7aNguao99mfWxHngA+=o5hwzjdOg@mail.gmail.com/ Tested-by: Zhiyu Zhang Signed-off-by: Zhiyu Zhang Reviewed-by: Phillip Lougher --- fs/squashfs/cache.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/squashfs/cache.c b/fs/squashfs/cache.c index 4db0d2b0aab8..181260e72680 100644 --- a/fs/squashfs/cache.c +++ b/fs/squashfs/cache.c @@ -198,7 +198,7 @@ void squashfs_cache_delete(struct squashfs_cache *cache) { int i, j; - if (cache == NULL) + if (IS_ERR(cache) || cache == NULL) return; for (i = 0; i < cache->entries; i++) {