kernel.git/fs/squashfs, branch linux-6.15.y

Squashfs: check return result of sb_min_blocksize

2025-06-19T13:40:11Z

[ Upstream commit 734aa85390ea693bb7eaf2240623d41b03705c84 ] Syzkaller reports an "UBSAN: shift-out-of-bounds in squashfs_bio_read" bug. Syzkaller forks multiple processes which after mounting the Squashfs filesystem, issues an ioctl("/dev/loop0", LOOP_SET_BLOCK_SIZE, 0x8000). Now if this ioctl occurs at the same time another process is in the process of mounting a Squashfs filesystem on /dev/loop0, the failure occurs. When this happens the following code in squashfs_fill_super() fails. ---- msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE); msblk->devblksize_log2 = ffz(~msblk->devblksize); ---- sb_min_blocksize() returns 0, which means msblk->devblksize is set to 0. As a result, ffz(~msblk->devblksize) returns 64, and msblk->devblksize_log2 is set to 64. This subsequently causes the UBSAN: shift-out-of-bounds in fs/squashfs/block.c:195:36 shift exponent 64 is too large for 64-bit type 'u64' (aka 'unsigned long long') This commit adds a check for a 0 return by sb_min_blocksize(). Link: https://lkml.kernel.org/r/20250409024747.876480-1-phillip@squashfs.org.uk Fixes: 0aa666190509 ("Squashfs: super block operations") Reported-by: syzbot+65761fc25a137b9c8c6e@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/67f0dd7a.050a0220.0a13.0230.GAE@google.com/ Signed-off-by: Phillip Lougher Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

squashfs: fix invalid pointer dereference in squashfs_cache_delete

2025-03-17T00:40:24Z

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. Link: https://lkml.kernel.org/r/20250306132855.2030-1-zhiyuzhang999@gmail.com Fixes: 49ff29240ebb ("squashfs: make squashfs_cache_init() return ERR_PTR(-ENOMEM)") Signed-off-by: Zhiyu Zhang Reported-by: Zhiyu Zhang Closes: https://lore.kernel.org/linux-fsdevel/CALf2hKvaq8B4u5yfrE+BYt7aNguao99mfWxHngA+=o5hwzjdOg@mail.gmail.com/ Tested-by: Zhiyu Zhang Reviewed-by: Phillip Lougher Signed-off-by: Andrew Morton

squashfs: convert squashfs_fill_page() to take a folio

2025-01-25T06:47:22Z

squashfs_fill_page is only used in this file, so make it static. Use kmap_local instead of kmap_atomic, and return a bool so that the caller can use folio_end_read() which saves an atomic operation over calling folio_mark_uptodate() followed by folio_unlock(). [willy@infradead.org: fix polarity of "uptodate" Thanks to Ryan for testing] Link: https://lkml.kernel.org/r/20250110163300.3346321-2-willy@infradead.org Link: https://lkml.kernel.org/r/20241220224634.723899-5-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Tested-by: Ryan Roberts Cc: Phillip Lougher Signed-off-by: Andrew Morton

squashfs; convert squashfs_copy_cache() to take a folio

2025-01-25T06:47:22Z

Remove accesses to page->index and page->mapping. Also use folio APIs where available. This code still assumes order 0 folios. [dan.carpenter@linaro.org: fix a NULL vs IS_ERR() bug] Link: https://lkml.kernel.org/r/7b7f44d6-9153-4d7c-b65b-2d78febe6c7a@stanley.mountain Link: https://lkml.kernel.org/r/20241220224634.723899-4-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Dan Carpenter Cc: Phillip Lougher Cc: Dan Carpenter Signed-off-by: Andrew Morton

squashfs: convert squashfs_readpage_block() to take a folio

2025-01-25T06:47:22Z

Remove a few accesses to page->mapping. Link: https://lkml.kernel.org/r/20241220224634.723899-3-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Cc: Phillip Lougher Signed-off-by: Andrew Morton

squashfs: pass a folio to squashfs_readpage_fragment()

2025-01-25T06:47:22Z

Remove an access to page->mapping. Link: https://lkml.kernel.org/r/20241220224634.723899-2-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Cc: Phillip Lougher Signed-off-by: Andrew Morton

squashfs: use a folio throughout squashfs_read_folio()

2025-01-25T06:47:22Z

Use modern folio APIs where they exist and convert back to struct page for the internal functions. Link: https://lkml.kernel.org/r/20241220224634.723899-1-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Cc: Phillip Lougher Signed-off-by: Andrew Morton

squashfs: update Kconfig information

2025-01-25T06:47:22Z

Update the compression algorithms supported, and the Squashfs website location. Link: https://lkml.kernel.org/r/20241229233752.54481-5-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher Signed-off-by: Andrew Morton

squashfs: don't allocate read_page cache if SQUASHFS_FILE_DIRECT configured

2025-01-25T06:47:21Z

If Squashfs has been configured to directly read datablocks into the page cache (SQUASHFS_FILE_DIRECT), then the read_page cache is unnecessary. This improvement is due to the following two commits, which added the ability to read datablocks into the page cache when pages were missing, enabling the fallback which used an intermediate buffer to be removed. commit f268eedddf359 ("squashfs: extend "page actor" to handle missing pages") commit 1bb1a07afad97 ("squashfs: don't use intermediate buffer if pages missing") This reduces the amount of memory used when mounting a filesystem by block_size * maximum number of threads. Link: https://lkml.kernel.org/r/20241229233752.54481-3-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher Signed-off-by: Andrew Morton

squashfs: make squashfs_cache_init() return ERR_PTR(-ENOMEM)

2025-01-25T06:45:34Z

Patch series "squashfs: reduce memory usage and update docs". This patchset reduces the amount of memory that Squashfs uses when CONFIG_FILE_DIRECT is configured, and updates various out of date information in the documentation and Kconfig. This patch (of 4): Make squashfs_cache_init() return an ERR_PTR(-ENOMEM) on failure rather than NULL. This tidies up some calling code, but, it also allows NULL to be returned as a valid result when a cache hasn't be allocated. Link: https://lkml.kernel.org/r/20241229233752.54481-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20241229233752.54481-2-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher Signed-off-by: Andrew Morton