kernel/linux.git/fs/proc/generic.c, branch v6.6.132

fs/proc: fix uaf in proc_readdir_de()

2025-11-24T09:30:07+00:00

commit 895b4c0c79b092d732544011c3cecaf7322c36a1 upstream. Pde is erased from subdir rbtree through rb_erase(), but not set the node to EMPTY, which may result in uaf access. We should use RB_CLEAR_NODE() set the erased node to EMPTY, then pde_subdir_next() will return NULL to avoid uaf access. We found an uaf issue while using stress-ng testing, need to run testcase getdent and tun in the same time. The steps of the issue is as follows: 1) use getdent to traverse dir /proc/pid/net/dev_snmp6/, and current pde is tun3; 2) in the [time windows] unregister netdevice tun3 and tun2, and erase them from rbtree. erase tun3 first, and then erase tun2. the pde(tun2) will be released to slab; 3) continue to getdent process, then pde_subdir_next() will return pde(tun2) which is released, it will case uaf access. CPU 0 | CPU 1 ------------------------------------------------------------------------- traverse dir /proc/pid/net/dev_snmp6/ | unregister_netdevice(tun->dev) //tun3 tun2 sys_getdents64() | iterate_dir() | proc_readdir() | proc_readdir_de() | snmp6_unregister_dev() pde_get(de); | proc_remove() read_unlock(&proc_subdir_lock); | remove_proc_subtree() | write_lock(&proc_subdir_lock); [time window] | rb_erase(&root->subdir_node, &parent->subdir); | write_unlock(&proc_subdir_lock); read_lock(&proc_subdir_lock); | next = pde_subdir_next(de); | pde_put(de); | de = next; //UAF | rbtree of dev_snmp6 | pde(tun3) / \ NULL pde(tun2) Link: https://lkml.kernel.org/r/20251025024233.158363-1-albin_yang@163.com Signed-off-by: Wei Yang Cc: Al Viro Cc: Christian Brauner Cc: wangzijie Cc: Alexey Dobriyan Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

proc: fix type confusion in pde_set_flags()

2025-09-19T14:32:02+00:00

[ Upstream commit 0ce9398aa0830f15f92bbed73853f9861c3e74ff ] Commit 2ce3d282bd50 ("proc: fix missing pde_set_flags() for net proc files") missed a key part in the definition of proc_dir_entry: union { const struct proc_ops *proc_ops; const struct file_operations *proc_dir_ops; }; So dereference of ->proc_ops assumes it is a proc_ops structure results in type confusion and make NULL check for 'proc_ops' not work for proc dir. Add !S_ISDIR(dp->mode) test before calling pde_set_flags() to fix it. Link: https://lkml.kernel.org/r/20250904135715.3972782-1-wangzijie1@honor.com Fixes: 2ce3d282bd50 ("proc: fix missing pde_set_flags() for net proc files") Signed-off-by: wangzijie Reported-by: Brad Spengler Closes: https://lore.kernel.org/all/20250903065758.3678537-1-wangzijie1@honor.com/ Cc: Alexey Dobriyan Cc: Al Viro Cc: Christian Brauner Cc: Jiri Slaby Cc: Stefano Brivio Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

proc: fix missing pde_set_flags() for net proc files

2025-09-09T16:56:26+00:00

commit 2ce3d282bd5050fca8577defeff08ada0d55d062 upstream. To avoid potential UAF issues during module removal races, we use pde_set_flags() to save proc_ops flags in PDE itself before proc_register(), and then use pde_has_proc_*() helpers instead of directly dereferencing pde->proc_ops->*. However, the pde_set_flags() call was missing when creating net related proc files. This omission caused incorrect behavior which FMODE_LSEEK was being cleared inappropriately in proc_reg_open() for net proc files. Lars reported it in this link[1]. Fix this by ensuring pde_set_flags() is called when register proc entry, and add NULL check for proc_ops in pde_set_flags(). [wangzijie1@honor.com: stash pde->proc_ops in a local const variable, per Christian] Link: https://lkml.kernel.org/r/20250821105806.1453833-1-wangzijie1@honor.com Link: https://lkml.kernel.org/r/20250818123102.959595-1-wangzijie1@honor.com Link: https://lore.kernel.org/all/20250815195616.64497967@chagall.paradoxon.rec/ [1] Fixes: ff7ec8dc1b64 ("proc: use the same treatment to check proc_lseek as ones for proc_read_iter et.al") Signed-off-by: wangzijie Reported-by: Lars Wendler Tested-by: Stefano Brivio Tested-by: Petr Vaněk Tested by: Lars Wendler Cc: Alexei Starovoitov Cc: Alexey Dobriyan Cc: Al Viro Cc: "Edgecombe, Rick P" Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: Kirill A. Shutemov Cc: wangzijie Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

proc: use the same treatment to check proc_lseek as ones for proc_read_iter et.al

2025-08-15T10:08:54+00:00

[ Upstream commit ff7ec8dc1b646296f8d94c39339e8d3833d16c05 ] Check pde->proc_ops->proc_lseek directly may cause UAF in rmmod scenario. It's a gap in proc_reg_open() after commit 654b33ada4ab("proc: fix UAF in proc_get_inode()"). Followed by AI Viro's suggestion, fix it in same manner. Link: https://lkml.kernel.org/r/20250607021353.1127963-1-wangzijie1@honor.com Fixes: 3f61631d47f1 ("take care to handle NULL ->proc_lseek()") Signed-off-by: wangzijie Reviewed-by: Alexey Dobriyan Cc: Alexei Starovoitov Cc: Al Viro Cc: "Edgecombe, Rick P" Cc: Kirill A. Shuemov Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

proc: fix UAF in proc_get_inode()

2025-03-28T20:59:55+00:00

commit 654b33ada4ab5e926cd9c570196fefa7bec7c1df upstream. Fix race between rmmod and /proc/XXX's inode instantiation. The bug is that pde->proc_ops don't belong to /proc, it belongs to a module, therefore dereferencing it after /proc entry has been registered is a bug unless use_pde/unuse_pde() pair has been used. use_pde/unuse_pde can be avoided (2 atomic ops!) because pde->proc_ops never changes so information necessary for inode instantiation can be saved _before_ proc_register() in PDE itself and used later, avoiding pde->proc_ops->... dereference. rmmod lookup sys_delete_module proc_lookup_de pde_get(de); proc_get_inode(dir->i_sb, de); mod->exit() proc_remove remove_proc_subtree proc_entry_rundown(de); free_module(mod); if (S_ISREG(inode->i_mode)) if (de->proc_ops->proc_read_iter) --> As module is already freed, will trigger UAF BUG: unable to handle page fault for address: fffffbfff80a702b PGD 817fc4067 P4D 817fc4067 PUD 817fc0067 PMD 102ef4067 PTE 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 26 UID: 0 PID: 2667 Comm: ls Tainted: G Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:proc_get_inode+0x302/0x6e0 RSP: 0018:ffff88811c837998 EFLAGS: 00010a06 RAX: dffffc0000000000 RBX: ffffffffc0538140 RCX: 0000000000000007 RDX: 1ffffffff80a702b RSI: 0000000000000001 RDI: ffffffffc0538158 RBP: ffff8881299a6000 R08: 0000000067bbe1e5 R09: 1ffff11023906f20 R10: ffffffffb560ca07 R11: ffffffffb2b43a58 R12: ffff888105bb78f0 R13: ffff888100518048 R14: ffff8881299a6004 R15: 0000000000000001 FS: 00007f95b9686840(0000) GS:ffff8883af100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffbfff80a702b CR3: 0000000117dd2000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: proc_lookup_de+0x11f/0x2e0 __lookup_slow+0x188/0x350 walk_component+0x2ab/0x4f0 path_lookupat+0x120/0x660 filename_lookup+0x1ce/0x560 vfs_statx+0xac/0x150 __do_sys_newstat+0x96/0x110 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e [adobriyan@gmail.com: don't do 2 atomic ops on the common path] Link: https://lkml.kernel.org/r/3d25ded0-1739-447e-812b-e34da7990dcf@p183 Fixes: 778f3dd5a13c ("Fix procfs compat_ioctl regression") Signed-off-by: Ye Bin Signed-off-by: Alexey Dobriyan Cc: Al Viro Cc: David S. Miller Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

fs: pass the request_mask to generic_fillattr

2023-08-09T06:56:36+00:00

generic_fillattr just fills in the entire stat struct indiscriminately today, copying data from the inode. There is at least one attribute (STATX_CHANGE_COOKIE) that can have side effects when it is reported, and we're looking at adding more with the addition of multigrain timestamps. Add a request_mask argument to generic_fillattr and have most callers just pass in the value that is passed to getattr. Have other callers (e.g. ksmbd) just pass in STATX_BASIC_STATS. Also move the setting of STATX_CHANGE_COOKIE into generic_fillattr. Acked-by: Joseph Qi Reviewed-by: Xiubo Li Reviewed-by: "Paulo Alcantara (SUSE)" Reviewed-by: Jan Kara Signed-off-by: Jeff Layton Message-Id: <20230807-mgctime-v7-2-d1dec143a704@kernel.org> Signed-off-by: Christian Brauner

proc: remove mark_inode_dirty() in .setattr()

2023-04-08T20:45:36+00:00

procfs' .setattr() has updated i_uid, i_gid and i_mode into proc dirent, we don't need to call mark_inode_dirty() for delayed update, remove it. Link: https://lkml.kernel.org/r/20230131150840.34726-1-chao@kernel.org Signed-off-by: Chao Yu Reviewed-by: Alexey Dobriyan Signed-off-by: Andrew Morton

fs: port ->getattr() to pass mnt_idmap

2023-01-19T08:24:25+00:00

Convert to struct mnt_idmap. Last cycle we merged the necessary infrastructure in 256c8aed2b42 ("fs: introduce dedicated idmap type for mounts"). This is just the conversion to struct mnt_idmap. Currently we still pass around the plain namespace that was attached to a mount. This is in general pretty convenient but it makes it easy to conflate namespaces that are relevant on the filesystem with namespaces that are relevent on the mount level. Especially for non-vfs developers without detailed knowledge in this area this can be a potential source for bugs. Once the conversion to struct mnt_idmap is done all helpers down to the really low-level helpers will take a struct mnt_idmap argument instead of two namespace arguments. This way it becomes impossible to conflate the two eliminating the possibility of any bugs. All of the vfs and all filesystems only operate on struct mnt_idmap. Acked-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Christian Brauner (Microsoft)

fs: port ->setattr() to pass mnt_idmap

2023-01-19T08:24:02+00:00

proc: fix dentry/inode overinstantiating under /proc/${pid}/net

2022-05-10T01:29:19+00:00

When a process exits, /proc/${pid}, and /proc/${pid}/net dentries are flushed. However some leaf dentries like /proc/${pid}/net/arp_cache aren't. That's because respective PDEs have proc_misc_d_revalidate() hook which returns 1 and leaves dentries/inodes in the LRU. Force revalidation/lookup on everything under /proc/${pid}/net by inheriting proc_net_dentry_ops. [akpm@linux-foundation.org: coding-style cleanups] Link: https://lkml.kernel.org/r/YjdVHgildbWO7diJ@localhost.localdomain Fixes: c6c75deda813 ("proc: fix lookup in /proc/net subdirectories after setns(2)") Signed-off-by: Alexey Dobriyan Reported-by: hui li Cc: Al Viro Signed-off-by: Andrew Morton