{"id":70545,"date":"2025-09-19T21:32:37","date_gmt":"2025-09-19T18:02:37","guid":{"rendered":"https:\/\/afaghhosting.net\/blog\/cve-2025-39866-fs-writeback-fix-use-after-free-in-__mark_inode_dirty\/"},"modified":"2025-09-19T21:32:37","modified_gmt":"2025-09-19T18:02:37","slug":"cve-2025-39866-fs-writeback-fix-use-after-free-in-__mark_inode_dirty","status":"publish","type":"post","link":"https:\/\/afaghhosting.net\/blog\/cve-2025-39866-fs-writeback-fix-use-after-free-in-__mark_inode_dirty\/","title":{"rendered":"CVE-2025-39866 – fs: writeback: fix use-after-free in __mark_inode_dirty()"},"content":{"rendered":"

CVE ID : <\/strong>CVE-2025-39866
\n
\nPublished : <\/strong> Sept. 19, 2025, 4:15 p.m. | 48\u00a0minutes ago
\n
\nDescription : <\/strong>In the Linux kernel, the following vulnerability has been resolved:<\/p>\n

fs: writeback: fix use-after-free in __mark_inode_dirty()<\/p>\n

An use-after-free issue occurred when __mark_inode_dirty() get the
\nbdi_writeback that was in the progress of switching.<\/p>\n

CPU: 1 PID: 562 Comm: systemd-random- Not tainted 6.6.56-gb4403bd46a8e #1
\n……
\npstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=–)
\npc : __mark_inode_dirty+0x124\/0x418
\nlr : __mark_inode_dirty+0x118\/0x418
\nsp : ffffffc08c9dbbc0
\n……..
\nCall trace:
\n __mark_inode_dirty+0x124\/0x418
\n generic_update_time+0x4c\/0x60
\n file_modified+0xcc\/0xd0
\n ext4_buffered_write_iter+0x58\/0x124
\n ext4_file_write_iter+0x54\/0x704
\n vfs_write+0x1c0\/0x308
\n ksys_write+0x74\/0x10c
\n __arm64_sys_write+0x1c\/0x28
\n invoke_syscall+0x48\/0x114
\n el0_svc_common.constprop.0+0xc0\/0xe0
\n do_el0_svc+0x1c\/0x28
\n el0_svc+0x40\/0xe4
\n el0t_64_sync_handler+0x120\/0x12c
\n el0t_64_sync+0x194\/0x198<\/p>\n

Root cause is:<\/p>\n

systemd-random-seed kworker
\n———————————————————————-
\n___mark_inode_dirty inode_switch_wbs_work_fn<\/p>\n

spin_lock(&inode->i_lock);
\n inode_attach_wb
\n locked_inode_to_wb_and_lock_list
\n get inode->i_wb
\n spin_unlock(&inode->i_lock);
\n spin_lock(&wb->list_lock)
\n spin_lock(&inode->i_lock)
\n inode_io_list_move_locked
\n spin_unlock(&wb->list_lock)
\n spin_unlock(&inode->i_lock)
\n spin_lock(&old_wb->list_lock)
\n inode_do_switch_wbs
\n spin_lock(&inode->i_lock)
\n inode->i_wb = new_wb
\n spin_unlock(&inode->i_lock)
\n spin_unlock(&old_wb->list_lock)
\n wb_put_many(old_wb, nr_switched)
\n cgwb_release
\n old wb released
\n wb_wakeup_delayed() accesses wb,
\n then trigger the use-after-free
\n issue<\/p>\n

Fix this race condition by holding inode spinlock until
\nwb_wakeup_delayed() finished.
\n
\nSeverity:<\/strong> 0.0 | NA
\n
\nVisit the link for more details, such as CVSS details, affected products, timeline, and more…<\/p>\n","protected":false},"excerpt":{"rendered":"

CVE ID : CVE-2025-39866 Published : Sept. 19, 2025, 4:15 p.m. | 48\u00a0minutes ago Description : In the Linux kernel, the following vulnerability has been resolved: fs: writeback: fix use-after-free in __mark_inode_dirty() An use-after-free issue occurred when __mark_inode_dirty() get the bdi_writeback that was in the progress of switching. CPU: 1 PID: 562 Comm: systemd-random- Not …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[],"class_list":["post-70545","post","type-post","status-publish","format-standard","hentry","category-vulnerability"],"_links":{"self":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts\/70545","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/comments?post=70545"}],"version-history":[{"count":0,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts\/70545\/revisions"}],"wp:attachment":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/media?parent=70545"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/categories?post=70545"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/tags?post=70545"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}