kernel/linux.git/fs/erofs, branch v5.15.211

erofs: fix unsigned underflow in z_erofs_lz4_handle_overlap()

2026-06-19T11:33:42+00:00

[ Upstream commit 21e161de2dc660b1bb70ef5b156ab8e6e1cca3ab ] Some crafted images can have illegal (!partial_decoding && m_llen < m_plen) extents, and the LZ4 inplace decompression path can be wrongly hit, but it cannot handle (outpages < inpages) properly: "outpages - inpages" wraps to a large value and the subsequent rq->out[] access reads past the decompressed_pages array. However, such crafted cases can correctly result in a corruption report in the normal LZ4 non-inplace path. Let's add an additional check to fix this for backporting. Reproducible image (base64-encoded gzipped blob): H4sIAJGR12kCA+3SPUoDQRgG4MkmkkZk8QRbRFIIi9hbpEjrHQI5ghfwCN5BLCzTGtLbBI+g dilSJo1CnIm7GEXFxhT6PDDwfrs73/ywIQD/1ePD4r7Ou6ETsrq4mu7XcWfj++Pb58nJU/9i PNtbjhan04/9GtX4qVYc814WDqt6FaX5s+ZwXXeq52lndT6IuVvlblytLMvh4Gzwaf90nsvz 2DF/21+20T/ldgp5s1jXRaN4t/8izsy/OUB6e/Qa79r+JwAAAAAAAL52vQVuGQAAAP6+my1w ywAAAAAAAADwu14ATsEYtgBQAAA= $ mount -t erofs -o cache_strategy=disabled foo.erofs /mnt $ dd if=/mnt/data of=/dev/null bs=4096 count=1 Fixes: 598162d05080 ("erofs: support decompress big pcluster for lz4 backend") Reported-by: Yuhao Jiang Cc: stable@vger.kernel.org Signed-off-by: Junrui Luo Reviewed-by: Gao Xiang Signed-off-by: Gao Xiang [ renamed `rq->outpages`/`rq->inpages` to `nrpages_out`/`nrpages_in` and inverted the check to `nrpages_out < nrpages_in` on the existing `goto docopy` chain ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

erofs: fix the out-of-bounds nameoff handling for trailing dirents

2026-06-19T11:33:41+00:00

[ Upstream commit d18a3b5d337fa412a38e776e6b4b857a58836575 ] Currently we already have boundary-checks for nameoffs, but the trailing dirents are special since the namelens are calculated with strnlen() with unchecked nameoffs. If a crafted EROFS has a trailing dirent with nameoff >= maxsize, maxsize - nameoff can underflow, causing strnlen() to read past the directory block. nameoff0 should also be verified to be a multiple of `sizeof(struct erofs_dirent)` as well [1]. [1] https://sashiko.dev/#/patchset/20260416063511.3173774-1-hsiangkao%40linux.alibaba.com Fixes: 3aa8ec716e52 ("staging: erofs: add directory operations") Fixes: 33bac912840f ("staging: erofs: keep corrupted fs from crashing kernel in erofs_readdir()") Reported-by: Yuhao Jiang Reported-by: Junrui Luo Closes: https://lore.kernel.org/r/A0FD7E0F-7558-49B0-8BC8-EB1ECDB2479A@outlook.com Cc: stable@vger.kernel.org Signed-off-by: Gao Xiang Reviewed-by: Chao Yu [ replaced upstream `bsz` with `PAGE_SIZE` and `sizeof(*de)` with `sizeof(struct erofs_dirent)` ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

erofs: add GFP_NOIO in the bio completion if needed

2026-04-18T08:33:27+00:00

commit c23df30915f83e7257c8625b690a1cece94142a0 upstream. The bio completion path in the process context (e.g. dm-verity) will directly call into decompression rather than trigger another workqueue context for minimal scheduling latencies, which can then call vm_map_ram() with GFP_KERNEL. Due to insufficient memory, vm_map_ram() may generate memory swapping I/O, which can cause submit_bio_wait to deadlock in some scenarios. Trimmed down the call stack, as follows: f2fs_submit_read_io submit_bio //bio_list is initialized. mmc_blk_mq_recovery z_erofs_endio vm_map_ram __pte_alloc_kernel __alloc_pages_direct_reclaim shrink_folio_list __swap_writepage submit_bio_wait //bio_list is non-NULL, hang!!! Use memalloc_noio_{save,restore}() to wrap up this path. Reviewed-by: Gao Xiang Signed-off-by: Jiucheng Xu Reviewed-by: Chao Yu Signed-off-by: Gao Xiang Signed-off-by: Greg Kroah-Hartman

minmax: add a few more MIN_T/MAX_T users

2025-10-19T14:21:52+00:00

[ Upstream commit 4477b39c32fdc03363affef4b11d48391e6dc9ff ] Commit 3a7e02c040b1 ("minmax: avoid overly complicated constant expressions in VM code") added the simpler MIN_T/MAX_T macros in order to avoid some excessive expansion from the rather complicated regular min/max macros. The complexity of those macros stems from two issues: (a) trying to use them in situations that require a C constant expression (in static initializers and for array sizes) (b) the type sanity checking and MIN_T/MAX_T avoids both of these issues. Now, in the whole (long) discussion about all this, it was pointed out that the whole type sanity checking is entirely unnecessary for min_t/max_t which get a fixed type that the comparison is done in. But that still leaves min_t/max_t unnecessarily complicated due to worries about the C constant expression case. However, it turns out that there really aren't very many cases that use min_t/max_t for this, and we can just force-convert those. This does exactly that. Which in turn will then allow for much simpler implementations of min_t()/max_t(). All the usual "macros in all upper case will evaluate the arguments multiple times" rules apply. We should do all the same things for the regular min/max() vs MIN/MAX() cases, but that has the added complexity of various drivers defining their own local versions of MIN/MAX, so that needs another level of fixes first. Link: https://lore.kernel.org/all/b47fad1d0cf8449886ad148f8c013dae@AcuMS.aculab.com/ Cc: David Laight Cc: Lorenzo Stoakes Signed-off-by: Linus Torvalds Signed-off-by: Eliav Farber Signed-off-by: Greg Kroah-Hartman

erofs: fix incorrect symlink detection in fast symlink

2025-01-09T12:28:30+00:00

commit 9ed50b8231e37b1ae863f5dec8153b98d9f389b4 upstream. Fast symlink can be used if the on-disk symlink data is stored in the same block as the on-disk inode, so we don’t need to trigger another I/O for symlink data. However, currently fs correction could be reported _incorrectly_ if inode xattrs are too large. In fact, these should be valid images although they cannot be handled as fast symlinks. Many thanks to Colin for reporting this! Reported-by: Colin Walters Reported-by: https://honggfuzz.dev/ Link: https://lore.kernel.org/r/bb2dd430-7de0-47da-ae5b-82ab2dd4d945@app.fastmail.com Fixes: 431339ba9042 ("staging: erofs: add inode operations") [ Note that it's a runtime misbehavior instead of a security issue. ] Link: https://lore.kernel.org/r/20240909031911.1174718-1-hsiangkao@linux.alibaba.com Signed-off-by: Gao Xiang Signed-off-by: Sasha Levin

erofs: apply proper VMA alignment for memory mapped files on THP

2024-03-15T14:48:15+00:00

[ Upstream commit 4127caee89612a84adedd78c9453089138cd5afe ] There are mainly two reasons that thp_get_unmapped_area() should be used for EROFS as other filesystems: - It's needed to enable PMD mappings as a FSDAX filesystem, see commit 74d2fad1334d ("thp, dax: add thp_get_unmapped_area for pmd mappings"); - It's useful together with large folios and CONFIG_READ_ONLY_THP_FOR_FS which enable THPs for mmapped files (e.g. shared libraries) even without FSDAX. See commit 1854bc6e2420 ("mm/readahead: Align file mappings for non-DAX"). Fixes: 06252e9ce05b ("erofs: dax support for non-tailpacking regular file") Fixes: ce529cc25b18 ("erofs: enable large folios for iomap mode") Fixes: e6687b89225e ("erofs: enable large folios for fscache mode") Reviewed-by: Jingbo Xu Reviewed-by: Chao Yu Signed-off-by: Gao Xiang Link: https://lore.kernel.org/r/20240306053138.2240206-1-hsiangkao@linux.alibaba.com Signed-off-by: Sasha Levin

erofs: fix lz4 inplace decompression

2024-03-01T12:21:48+00:00

commit 3c12466b6b7bf1e56f9b32c366a3d83d87afb4de upstream. Currently EROFS can map another compressed buffer for inplace decompression, that was used to handle the cases that some pages of compressed data are actually not in-place I/O. However, like most simple LZ77 algorithms, LZ4 expects the compressed data is arranged at the end of the decompressed buffer and it explicitly uses memmove() to handle overlapping: __________________________________________________________ |_ direction of decompression --> ____ |_ compressed data _| Although EROFS arranges compressed data like this, it typically maps two individual virtual buffers so the relative order is uncertain. Previously, it was hardly observed since LZ4 only uses memmove() for short overlapped literals and x86/arm64 memmove implementations seem to completely cover it up and they don't have this issue. Juhyung reported that EROFS data corruption can be found on a new Intel x86 processor. After some analysis, it seems that recent x86 processors with the new FSRM feature expose this issue with "rep movsb". Let's strictly use the decompressed buffer for lz4 inplace decompression for now. Later, as an useful improvement, we could try to tie up these two buffers together in the correct order. Reported-and-tested-by: Juhyung Park Closes: https://lore.kernel.org/r/CAD14+f2AVKf8Fa2OO1aAUdDNTDsVzzR6ctU_oJSmTyd6zSYR2Q@mail.gmail.com Fixes: 0ffd71bcc3a0 ("staging: erofs: introduce LZ4 decompression inplace") Fixes: 598162d05080 ("erofs: support decompress big pcluster for lz4 backend") Cc: stable # 5.4+ Tested-by: Yifan Zhao Signed-off-by: Gao Xiang Link: https://lore.kernel.org/r/20231206045534.3920847-1-hsiangkao@linux.alibaba.com Signed-off-by: Greg Kroah-Hartman

erofs: ensure that the post-EOF tails are all zeroed

2023-09-06T20:28:37+00:00

commit e4c1cf523d820730a86cae2c6d55924833b6f7ac upstream. This was accidentally fixed up in commit e4c1cf523d82 but we can't take the full change due to other dependancy issues, so here is just the actual bugfix that is needed. [Background] keltargw reported an issue [1] that with mmaped I/Os, sometimes the tail of the last page (after file ends) is not filled with zeroes. The root cause is that such tail page could be wrongly selected for inplace I/Os so the zeroed part will then be filled with compressed data instead of zeroes. A simple fix is to avoid doing inplace I/Os for such tail parts, actually that was already fixed upstream in commit e4c1cf523d82 ("erofs: tidy up z_erofs_do_read_page()") by accident. [1] https://lore.kernel.org/r/3ad8b469-25db-a297-21f9-75db2d6ad224@linux.alibaba.com Reported-by: keltargw Fixes: 3883a79abd02 ("staging: erofs: introduce VLE decompression support") Signed-off-by: Gao Xiang Signed-off-by: Greg Kroah-Hartman

erofs: fix compact 4B support for 16k block size

2023-07-23T11:47:48+00:00

commit 001b8ccd0650727e54ec16ef72bf1b8eeab7168e upstream. In compact 4B, two adjacent lclusters are packed together as a unit to form on-disk indexes for effective random access, as below: (amortized = 4, vcnt = 2) _____________________________________________ |___@_____ encoded bits __________|_ blkaddr _| 0 . amortized * vcnt = 8 . . . . amortized * vcnt - 4 = 4 . . .____________________________. |_type (2 bits)_|_clusterofs_| Therefore, encoded bits for each pack are 32 bits (4 bytes). IOWs, since each lcluster can get 16 bits for its type and clusterofs, the maximum supported lclustersize for compact 4B format is 16k (14 bits). Fix this to enable compact 4B format for 16k lclusters (blocks), which is tested on an arm64 server with 16k page size. Fixes: 152a333a5895 ("staging: erofs: add compacted compression indexes support") Signed-off-by: Gao Xiang Link: https://lore.kernel.org/r/20230601112341.56960-1-hsiangkao@linux.alibaba.com Signed-off-by: Greg Kroah-Hartman

erofs: fix fsdax unavailability for chunk-based regular files

2023-07-23T11:47:44+00:00

[ Upstream commit 18bddc5b67038722cb88fcf51fbf41a0277092cb ] DAX can be used to share page cache between VMs, reducing guest memory overhead. And chunk based data format is widely used for VM and container image. So enable dax support for it, make erofs better used for VM scenarios. Fixes: c5aa903a59db ("erofs: support reading chunk-based uncompressed files") Signed-off-by: Xin Yin Reviewed-by: Gao Xiang Reviewed-by: Chao Yu Link: https://lore.kernel.org/r/20230711062130.7860-1-yinxin.x@bytedance.com Signed-off-by: Gao Xiang Signed-off-by: Sasha Levin