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 --- net/ipv4/fib_notifier.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 net/ipv4/fib_notifier.c (limited to 'net/ipv4/fib_notifier.c') diff --git a/net/ipv4/fib_notifier.c b/net/ipv4/fib_notifier.c new file mode 100644 index 000000000..b1551c265 --- /dev/null +++ b/net/ipv4/fib_notifier.c @@ -0,0 +1,72 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include + +int call_fib4_notifier(struct notifier_block *nb, + enum fib_event_type event_type, + struct fib_notifier_info *info) +{ + info->family = AF_INET; + return call_fib_notifier(nb, event_type, info); +} + +int call_fib4_notifiers(struct net *net, enum fib_event_type event_type, + struct fib_notifier_info *info) +{ + ASSERT_RTNL(); + + info->family = AF_INET; + /* Paired with READ_ONCE() in fib4_seq_read() */ + WRITE_ONCE(net->ipv4.fib_seq, net->ipv4.fib_seq + 1); + return call_fib_notifiers(net, event_type, info); +} + +static unsigned int fib4_seq_read(const struct net *net) +{ + /* Paired with WRITE_ONCE() in call_fib4_notifiers() */ + return READ_ONCE(net->ipv4.fib_seq) + fib4_rules_seq_read(net); +} + +static int fib4_dump(struct net *net, struct notifier_block *nb, + struct netlink_ext_ack *extack) +{ + int err; + + err = fib4_rules_dump(net, nb, extack); + if (err) + return err; + + return fib_notify(net, nb, extack); +} + +static const struct fib_notifier_ops fib4_notifier_ops_template = { + .family = AF_INET, + .fib_seq_read = fib4_seq_read, + .fib_dump = fib4_dump, + .owner = THIS_MODULE, +}; + +int __net_init fib4_notifier_init(struct net *net) +{ + struct fib_notifier_ops *ops; + + net->ipv4.fib_seq = 0; + + ops = fib_notifier_ops_register(&fib4_notifier_ops_template, net); + if (IS_ERR(ops)) + return PTR_ERR(ops); + net->ipv4.notifier_ops = ops; + + return 0; +} + +void __net_exit fib4_notifier_exit(struct net *net) +{ + fib_notifier_ops_unregister(net->ipv4.notifier_ops); +} -- cgit v1.3.1