kernel/linux.git/fs/gfs2, branch v6.6.144

gfs2: fix use-after-free in gfs2_qd_dealloc

2026-07-04T11:42:26+00:00

commit f9c9ec2c319f843b70ecdf939d48b52d189bc081 upstream. gfs2_qd_dealloc(), called as an RCU callback from gfs2_qd_dispose(), accesses the superblock object sdp through qd->qd_sbd after freeing qd. It does so to decrement sd_quota_count and wake up sd_kill_wait. However, by the time the RCU callback runs, gfs2_put_super() may have already freed sdp via free_sbd(). This can happen when gfs2_quota_cleanup() is called during unmount: it disposes of quota objects via call_rcu() and then waits on sd_kill_wait with a 60-second timeout. If the timeout expires, or if gfs2_gl_hash_clear() triggers additional qd_put() calls that schedule more RCU callbacks after the wait completes, gfs2_put_super() will proceed to free the superblock while RCU callbacks referencing it are still pending. Add an rcu_barrier() before free_sbd() in gfs2_put_super() to ensure all pending RCU callbacks (including gfs2_qd_dealloc) have completed before the superblock is freed. Fixes: a475c5dd16e5 ("gfs2: Free quota data objects synchronously") Reported-by: syzbot+42a37bf8045847d8f9d2@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=42a37bf8045847d8f9d2 Tested-by: syzbot+42a37bf8045847d8f9d2@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Signed-off-by: Tristan Madani Signed-off-by: Andreas Gruenbacher Signed-off-by: Greg Kroah-Hartman

gfs2: prevent NULL pointer dereference during unmount

2026-05-23T11:03:15+00:00

[ Upstream commit 74b4dbb946060a3233604d91859a9abd3708141d ] When flushing out outstanding glock work during an unmount, gfs2_log_flush() can be called when sdp->sd_jdesc has already been deallocated and sdp->sd_jdesc is NULL. Commit 35264909e9d1 ("gfs2: Fix NULL pointer dereference in gfs2_log_flush") added a check for that to gfs2_log_flush() itself, but it missed the sdp->sd_jdesc dereference in gfs2_log_release(). Fix that. Reported-by: kernel test robot Reported-by: Dan Carpenter Closes: https://lore.kernel.org/r/202604071139.HNJiCaAi-lkp@intel.com/ Fixes: 35264909e9d1 ("gfs2: Fix NULL pointer dereference in gfs2_log_flush") Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin

gfs2: add some missing log locking

2026-05-23T11:03:15+00:00

[ Upstream commit fe2c8d051150b90b3ccb85f89e3b1d636cb88ec8 ] Function gfs2_logd() calls the log flushing functions gfs2_ail1_start(), gfs2_ail1_wait(), and gfs2_ail1_empty() without holding sdp->sd_log_flush_lock, but these functions require exclusion against concurrent transactions. To fix that, add a non-locking __gfs2_log_flush() function. Then, in gfs2_logd(), take sdp->sd_log_flush_lock before calling the above mentioned log flushing functions and __gfs2_log_flush(). Fixes: 5e4c7632aae1c ("gfs2: Issue revokes more intelligently") Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin

gfs2: Call unlock_new_inode before d_instantiate

2026-05-23T11:03:15+00:00

[ Upstream commit 2ff7cf7e0640ff071ebc5c7e3dc2df024a7c91e6 ] As Neil Brown describes in detail in the link referenced below, new inodes must be unlocked before they can be instantiated. An even better fix is to use d_instantiate_new(), which combines d_instantiate() and unlock_new_inode(). Fixes: 3d36e57ff768 ("gfs2: gfs2_create_inode rework") Reported-by: syzbot+0ea5108a1f5fb4fcc2d8@syzkaller.appspotmail.com Link: https://lore.kernel.org/linux-fsdevel/177153754005.8396.8777398743501764194@noble.neil.brown.name/ Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin

gfs2: Validate i_depth for exhash directories

2026-04-11T12:19:34+00:00

[ Upstream commit 557c024ca7250bb65ae60f16c02074106c2f197b ] A fuzzer test introduced corruption that ends up with a depth of 0 in dir_e_read(), causing an undefined shift by 32 at: index = hash >> (32 - dip->i_depth); As calculated in an open-coded way in dir_make_exhash(), the minimum depth for an exhash directory is ilog2(sdp->sd_hash_ptrs) and 0 is invalid as sdp->sd_hash_ptrs is fixed as sdp->bsize / 16 at mount time. So we can avoid the undefined behaviour by checking for depth values lower than the minimum in gfs2_dinode_in(). Values greater than the maximum are already being checked for there. Also switch the calculation in dir_make_exhash() to use ilog2() to clarify how the depth is calculated. Tested with the syzkaller repro.c and xfstests '-g quick'. Reported-by: syzbot+4708579bb230a0582a57@syzkaller.appspotmail.com Signed-off-by: Andrew Price Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin

gfs2: Improve gfs2_consist_inode() usage

2026-04-11T12:19:33+00:00

[ Upstream commit 10398ef57aa189153406c110f5957145030f08fe ] gfs2_consist_inode() logs an error message with the source file and line number. When we jump before calling it, the line number becomes less useful as it no longer relates to the source of the error. To aid troubleshooting, replace the gotos with the gfs2_consist_inode() calls so that the error messages are more informative. Signed-off-by: Andrew Price Signed-off-by: Andreas Gruenbacher Signed-off-by: Ruohan Lan Signed-off-by: Sasha Levin

gfs2: Fix unlikely race in gdlm_put_lock

2026-04-02T11:07:30+00:00

[ Upstream commit 28c4d9bc0708956c1a736a9e49fee71b65deee81 ] In gdlm_put_lock(), there is a small window of time in which the DFL_UNMOUNT flag has been set but the lockspace hasn't been released, yet. In that window, dlm may still call gdlm_ast() and gdlm_bast(). To prevent it from dereferencing freed glock objects, only free the glock if the lockspace has actually been released. Signed-off-by: Andreas Gruenbacher Reviewed-by: Andrew Price [ Minor context change fixed. ] Signed-off-by: Robert Garcia Signed-off-by: Greg Kroah-Hartman

gfs2: fiemap page fault fix

2026-03-04T12:20:32+00:00

[ Upstream commit e411d74cc5ba290f85d0dd5e4d1df8f1d6d975d2 ] In gfs2_fiemap(), we are calling iomap_fiemap() while holding the inode glock. This can lead to recursive glock taking if the fiemap buffer is memory mapped to the same inode and accessing it triggers a page fault. Fix by disabling page faults for iomap_fiemap() and faulting in the buffer by hand if necessary. Fixes xfstest generic/742. Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin

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

2026-03-04T12:19:24+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

2026-03-04T12:19:24+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