From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- fs/hpfs/dentry.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 fs/hpfs/dentry.c (limited to 'fs/hpfs/dentry.c') diff --git a/fs/hpfs/dentry.c b/fs/hpfs/dentry.c new file mode 100644 index 000000000..89a36fdc6 --- /dev/null +++ b/fs/hpfs/dentry.c @@ -0,0 +1,62 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/fs/hpfs/dentry.c + * + * Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999 + * + * dcache operations + */ + +#include "hpfs_fn.h" + +/* + * Note: the dentry argument is the parent dentry. + */ + +static int hpfs_hash_dentry(const struct dentry *dentry, struct qstr *qstr) +{ + unsigned long hash; + int i; + unsigned l = qstr->len; + + if (l == 1) if (qstr->name[0]=='.') goto x; + if (l == 2) if (qstr->name[0]=='.' || qstr->name[1]=='.') goto x; + hpfs_adjust_length(qstr->name, &l); + /*if (hpfs_chk_name(qstr->name,&l))*/ + /*return -ENAMETOOLONG;*/ + /*return -ENOENT;*/ + x: + + hash = init_name_hash(dentry); + for (i = 0; i < l; i++) + hash = partial_name_hash(hpfs_upcase(hpfs_sb(dentry->d_sb)->sb_cp_table,qstr->name[i]), hash); + qstr->hash = end_name_hash(hash); + + return 0; +} + +static int hpfs_compare_dentry(const struct dentry *dentry, + unsigned int len, const char *str, const struct qstr *name) +{ + unsigned al = len; + unsigned bl = name->len; + + hpfs_adjust_length(str, &al); + /*hpfs_adjust_length(b->name, &bl);*/ + + /* + * 'str' is the nane of an already existing dentry, so the name + * must be valid. 'name' must be validated first. + */ + + if (hpfs_chk_name(name->name, &bl)) + return 1; + if (hpfs_compare_names(dentry->d_sb, str, al, name->name, bl, 0)) + return 1; + return 0; +} + +const struct dentry_operations hpfs_dentry_operations = { + .d_hash = hpfs_hash_dentry, + .d_compare = hpfs_compare_dentry, +}; -- cgit v1.3.1