From: Yun Zhou Date: Thu, 20 Nov 2025 15:43:50 +0000 (+0800) Subject: jfs: add dtroot integrity check to prevent index out-of-bounds X-Git-Tag: v7.1-rc1~133^2~7 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=c83abc766aeb153e69cb46363bf7c9de0c9f3268;p=thirdparty%2Fkernel%2Flinux.git jfs: add dtroot integrity check to prevent index out-of-bounds Add check_dtroot() to validate dtroot_t integrity, focusing on preventing index/pointer overflows from on-disk corruption. Key checks: - freecnt bounded by [0, DTROOTMAXSLOT-1] (slot[0] reserved for header). - freelist validity: -1 when freecnt=0; 1~DTROOTMAXSLOT-1 when non-zero, with linked list checks (no duplicates, proper termination via next=-1). - stbl bounds: nextindex within stbl array size; entries within 0~8, no duplicates (excluding idx=0). Invoked in copy_from_dinode() when loading directory inodes, catching corruption early before directory operations trigger out-of-bounds access. This fixes the following UBSAN warning. [ 101.832754][ T5960] ------------[ cut here ]------------ [ 101.832762][ T5960] UBSAN: array-index-out-of-bounds in fs/jfs/jfs_dtree.c:3713:8 [ 101.832792][ T5960] index -1 is out of range for type 'struct dtslot[128]' [ 101.832807][ T5960] CPU: 2 UID: 0 PID: 5960 Comm: 5f7f0caf9979e9d Tainted: G E 6.18.0-rc4-00250-g2603eb907f03 #119 PREEMPT_{RT,(full [ 101.832817][ T5960] Tainted: [E]=UNSIGNED_MODULE [ 101.832819][ T5960] Hardware name: QEMU Ubuntu 25.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 101.832823][ T5960] Call Trace: [ 101.832833][ T5960] [ 101.832838][ T5960] dump_stack_lvl+0x189/0x250 [ 101.832909][ T5960] ? __pfx_dump_stack_lvl+0x10/0x10 [ 101.832925][ T5960] ? __pfx__printk+0x10/0x10 [ 101.832934][ T5960] ? rt_mutex_slowunlock+0x493/0x8a0 [ 101.832959][ T5960] ubsan_epilogue+0xa/0x40 [ 101.832966][ T5960] __ubsan_handle_out_of_bounds+0xe9/0xf0 [ 101.833007][ T5960] dtInsertEntry+0x936/0x1430 [jfs] [ 101.833094][ T5960] dtSplitPage+0x2c8b/0x3ed0 [jfs] [ 101.833177][ T5960] ? __pfx_rt_mutex_slowunlock+0x10/0x10 [ 101.833193][ T5960] dtInsert+0x109b/0x6000 [jfs] [ 101.833283][ T5960] ? rt_mutex_slowunlock+0x493/0x8a0 [ 101.833296][ T5960] ? __pfx_rt_mutex_slowunlock+0x10/0x10 [ 101.833307][ T5960] ? rt_spin_unlock+0x161/0x200 [ 101.833315][ T5960] ? __pfx_dtInsert+0x10/0x10 [jfs] [ 101.833391][ T5960] ? txLock+0xaf9/0x1cb0 [jfs] [ 101.833477][ T5960] ? dtInitRoot+0x22a/0x670 [jfs] [ 101.833556][ T5960] jfs_mkdir+0x6ec/0xa70 [jfs] [ 101.833636][ T5960] ? __pfx_jfs_mkdir+0x10/0x10 [jfs] [ 101.833721][ T5960] ? generic_permission+0x2e5/0x690 [ 101.833760][ T5960] ? bpf_lsm_inode_mkdir+0x9/0x20 [ 101.833776][ T5960] vfs_mkdir+0x306/0x510 [ 101.833786][ T5960] do_mkdirat+0x247/0x590 [ 101.833795][ T5960] ? __pfx_do_mkdirat+0x10/0x10 [ 101.833804][ T5960] ? getname_flags+0x1e5/0x540 [ 101.833815][ T5960] __x64_sys_mkdir+0x6c/0x80 [ 101.833823][ T5960] do_syscall_64+0xfa/0xfa0 [ 101.833832][ T5960] ? lockdep_hardirqs_on+0x9c/0x150 [ 101.833840][ T5960] ? entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 101.833847][ T5960] ? exc_page_fault+0xab/0x100 [ 101.833856][ T5960] entry_SYSCALL_64_after_hwframe+0x77/0x7f Signed-off-by: Yun Zhou Signed-off-by: Dave Kleikamp --- diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c index 9ab3f2fc61d17..8abd9c7663ea4 100644 --- a/fs/jfs/jfs_dtree.c +++ b/fs/jfs/jfs_dtree.c @@ -4297,3 +4297,89 @@ int dtModify(tid_t tid, struct inode *ip, return 0; } + +bool check_dtroot(dtroot_t *p) +{ + DECLARE_BITMAP(bitmap, DTROOTMAXSLOT) = {0}; + int i; + + /* freecnt cannot be negative or exceed DTROOTMAXSLOT-1 + * (since slot[0] is occupied by the header). + */ + if (unlikely(p->header.freecnt < 0 || + p->header.freecnt > DTROOTMAXSLOT - 1)) { + jfs_err("Bad freecnt:%d in dtroot\n", p->header.freecnt); + return false; + } else if (p->header.freecnt == 0) { + /* No free slots: freelist must be -1 */ + if (unlikely(p->header.freelist != -1)) { + jfs_err("freecnt=0, but freelist=%d in dtroot\n", + p->header.freelist); + return false; + } + } else { + int fsi, i; + /* When there are free slots, freelist must be a valid slot index in + * 1~DTROOTMAXSLOT-1(since slot[0] is occupied by the header). + */ + if (unlikely(p->header.freelist < 1 || + p->header.freelist >= DTROOTMAXSLOT)) { + jfs_err("Bad freelist:%d in dtroot\n", p->header.freelist); + return false; + } + + /* Traverse the free list to check validity of all node indices */ + fsi = p->header.freelist; + for (i = 0; i < p->header.freecnt - 1; i++) { + /* Check for duplicate indices in the free list */ + if (unlikely(__test_and_set_bit(fsi, bitmap))) { + jfs_err("duplicate index%d in slot in dtroot\n", fsi); + return false; + } + fsi = p->slot[fsi].next; + + /* Ensure the next slot index in the free list is valid */ + if (unlikely(fsi < 1 || fsi >= DTROOTMAXSLOT)) { + jfs_err("Bad index:%d in slot in dtroot\n", fsi); + return false; + } + } + + /* The last node in the free list must terminate with next = -1 */ + if (unlikely(p->slot[fsi].next != -1)) { + jfs_err("Bad next:%d of the last slot in dtroot\n", + p->slot[fsi].next); + return false; + } + } + + /* Validate nextindex (next free entry index in stbl) + * stbl array has size 8 (indices 0~7). + * It may get set to 8 when the last free slot has been filled. + */ + if (unlikely(p->header.nextindex > ARRAY_SIZE(p->header.stbl))) { + jfs_err("Bad nextindex:%d in dtroot\n", p->header.nextindex); + return false; + } + + /* Validate index validity of stbl array (8 elements) + * Each entry in stbl is a slot index, with valid range: -1 (invalid) + * or 0~8 (slot[0]~slot[8]) + */ + for (i = 0; i < p->header.nextindex; i++) { + int idx = p->header.stbl[i]; + + if (unlikely(idx < 0 || idx >= 9)) { + jfs_err("Bad index:%d of stbl[%d] in dtroot\n", idx, i); + return false; /* stbl entry points out of slot array range */ + } + + /* Check for duplicate valid indices (skip check for idx=0) */ + if (unlikely(idx && __test_and_set_bit(idx, bitmap))) { + jfs_err("Duplicate index:%d in stbl in dtroot\n", idx); + return false; + } + } + + return true; +} diff --git a/fs/jfs/jfs_dtree.h b/fs/jfs/jfs_dtree.h index 1758289647a0e..94dc16123c87e 100644 --- a/fs/jfs/jfs_dtree.h +++ b/fs/jfs/jfs_dtree.h @@ -253,4 +253,6 @@ extern int dtModify(tid_t tid, struct inode *ip, struct component_name * key, ino_t * orig_ino, ino_t new_ino, int flag); extern int jfs_readdir(struct file *file, struct dir_context *ctx); + +extern bool check_dtroot(dtroot_t *p); #endif /* !_H_JFS_DTREE */ diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c index 294a67327c735..fbb5f7966b754 100644 --- a/fs/jfs/jfs_imap.c +++ b/fs/jfs/jfs_imap.c @@ -3102,6 +3102,10 @@ static int copy_from_dinode(struct dinode * dip, struct inode *ip) if (S_ISDIR(ip->i_mode)) { memcpy(&jfs_ip->u.dir, &dip->u._dir, 384); + if (!check_dtroot(&jfs_ip->i_dtroot)) { + jfs_error(ip->i_sb, "Corrupt dtroot\n"); + return -EIO; + } } else if (S_ISREG(ip->i_mode) || S_ISLNK(ip->i_mode)) { memcpy(&jfs_ip->i_xtroot, &dip->di_xtroot, 288); } else