kernel/linux.git/fs/gfs2/bmap.c, branch v5.15.213

gfs2: Fix use-after-free in iomap inline data write path

2026-03-04T12:19:21+00:00

[ Upstream commit faddeb848305e79db89ee0479bb0e33380656321 ] The inline data buffer head (dibh) is being released prematurely in gfs2_iomap_begin() via release_metapath() while iomap->inline_data still points to dibh->b_data. This causes a use-after-free when iomap_write_end_inline() later attempts to write to the inline data area. The bug sequence: 1. gfs2_iomap_begin() calls gfs2_meta_inode_buffer() to read inode metadata into dibh 2. Sets iomap->inline_data = dibh->b_data + sizeof(struct gfs2_dinode) 3. Calls release_metapath() which calls brelse(dibh), dropping refcount to 0 4. kswapd reclaims the page (~39ms later in the syzbot report) 5. iomap_write_end_inline() tries to memcpy() to iomap->inline_data 6. KASAN detects use-after-free write to freed memory Fix by storing dibh in iomap->private and incrementing its refcount with get_bh() in gfs2_iomap_begin(). The buffer is then properly released in gfs2_iomap_end() after the inline write completes, ensuring the page stays alive for the entire iomap operation. Note: A C reproducer is not available for this issue. The fix is based on analysis of the KASAN report and code review showing the buffer head is freed before use. [agruenba: Take buffer head reference in gfs2_iomap_begin() to avoid leaks in gfs2_iomap_get() and gfs2_iomap_alloc().] Reported-by: syzbot+ea1cd4aa4d1e98458a55@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=ea1cd4aa4d1e98458a55 Fixes: d0a22a4b03b8 ("gfs2: Fix iomap write page reclaim deadlock") Signed-off-by: Deepanshu Kartikey Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin

gfs2: Add metapath_dibh helper

2026-03-04T12:19:21+00:00

[ Upstream commit 92099f0c92270c8c7a79e6bc6e0312ad248ea331 ] Add a metapath_dibh() helper for extracting the inode's buffer head from a metapath. Signed-off-by: Andreas Gruenbacher Stable-dep-of: faddeb848305 ("gfs2: Fix use-after-free in iomap inline data write path") Signed-off-by: Sasha Levin

gfs2: Fix invalid metadata access in punch_hole

2024-05-17T09:50:52+00:00

[ Upstream commit c95346ac918c5badf51b9a7ac58a26d3bd5bb224 ] In punch_hole(), when the offset lies in the final block for a given height, there is no hole to punch, but the maximum size check fails to detect that. Consequently, punch_hole() will try to punch a hole beyond the end of the metadata and fail. Fix the maximum size check. Signed-off-by: Andrew Price Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin

gfs2: Always check inode size of inline inodes

2023-02-09T10:26:48+00:00

commit 70376c7ff31221f1d21db5611d8209e677781d3a upstream. Check if the inode size of stuffed (inline) inodes is within the allowed range when reading inodes from disk (gfs2_dinode_in()). This prevents us from on-disk corruption. The two checks in stuffed_readpage() and gfs2_unstuffer_page() that just truncate inline data to the maximum allowed size don't actually make sense, and they can be removed now as well. Reported-by: syzbot+7bb81dfa9cda07d9cd9d@syzkaller.appspotmail.com Signed-off-by: Andreas Gruenbacher Signed-off-by: Greg Kroah-Hartman

gfs2: Fix filesystem block deallocation for short writes

2022-05-18T08:26:51+00:00

[ Upstream commit d031a8866e709c9d1ee5537a321b6192b4d2dc5b ] When a write cannot be carried out in full, gfs2_iomap_end() releases blocks that have been allocated for this write but haven't been used. To compute the end of the allocation, gfs2_iomap_end() incorrectly rounded the end of the attempted write down to the next block boundary to arrive at the end of the allocation. It would have to round up, but the end of the allocation is also available as iomap->offset + iomap->length, so just use that instead. In addition, use round_up() for computing the start of the unused range. Fixes: 64bc06bb32ee ("gfs2: iomap buffered write support") Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin

gfs2: Move the inode glock locking to gfs2_file_buffered_write

2022-05-01T15:22:30+00:00

commit b924bdab7445946e2ed364a0e6e249d36f1f1158 upstream So far, for buffered writes, we were taking the inode glock in gfs2_iomap_begin and dropping it in gfs2_iomap_end with the intention of not holding the inode glock while iomap_write_actor faults in user pages. It turns out that iomap_write_actor is called inside iomap_begin ... iomap_end, so the user pages were still faulted in while holding the inode glock and the locking code in iomap_begin / iomap_end was completely pointless. Move the locking into gfs2_file_buffered_write instead. We'll take care of the potential deadlocks due to faulting in user pages while holding a glock in a subsequent patch. Signed-off-by: Andreas Gruenbacher Signed-off-by: Anand Jain Signed-off-by: Greg Kroah-Hartman

gfs2: gfs2_setattr_size error path fix

2022-04-08T12:24:10+00:00

commit 7336905a89f19173bf9301cd50a24421162f417c upstream. When gfs2_setattr_size() fails, it calls gfs2_rs_delete(ip, NULL) to get rid of any reservations the inode may have. Instead, it should pass in the inode's write count as the second parameter to allow gfs2_rs_delete() to figure out if the inode has any writers left. In a next step, there are two instances of gfs2_rs_delete(ip, NULL) left where we know that there can be no other users of the inode. Replace those with gfs2_rs_deltree(&ip->i_res) to avoid the unnecessary write count check. With that, gfs2_rs_delete() is only called with the inode's actual write count, so get rid of the second parameter. Fixes: a097dc7e24cb ("GFS2: Make rgrp reservations part of the gfs2_inode structure") Signed-off-by: Andreas Gruenbacher Signed-off-by: Greg Kroah-Hartman

gfs2: Fix length of holes reported at end-of-file

2021-12-08T08:04:37+00:00

[ Upstream commit f3506eee81d1f700d9ee2d2f4a88fddb669ec032 ] Fix the length of holes reported at the end of a file: the length is relative to the beginning of the extent, not the seek position which is rounded down to the filesystem block size. This bug went unnoticed for some time, but is now caught by the following assertion in iomap_iter_done(): WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos) Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin

iomap: remove the iomap arguments to ->page_{prepare,done}

2021-08-17T04:26:33+00:00

These aren't actually used by the only instance implementing the methods. Signed-off-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong

gfs2: Clean up gfs2_unstuff_dinode

2021-06-29T08:56:51+00:00

Split __gfs2_unstuff_inode off from gfs2_unstuff_dinode and clean up the code a little. All remaining callers now pass NULL as the page argument of gfs2_unstuff_dinode, so remove that argument. Signed-off-by: Andreas Gruenbacher