linux-kernel - [PATCH v2 1/2] static_call: Fix a wild-memory-access bug in static_call_del

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Date:   Fri, 15 Sep 2023 20:36:04 +0800
From:   Jinjie Ruan <ruanjinjie@...wei.com>
To:     <peterz@...radead.org>, <tglx@...utronix.de>,
        <rostedt@...dmis.org>, <mingo@...nel.org>, <jpoimboe@...nel.org>,
        <christophe.leroy@...roup.eu>, <linux-kernel@...r.kernel.org>
CC:     <ruanjinjie@...wei.com>
Subject: [PATCH v2 1/2] static_call: Fix a wild-memory-access bug in static_call_del_module()

Inject fault while probing btrfs.ko, if the first kzalloc() fails
in __static_call_init(), key->mods will all no be initialized in this
site and subsequent sites. And then in static_call_del_module() the
site_mod->mod will cause wild-memory-access as below.

To fix the issue, assign key->mods to NULL in __static_call_init() if it
fails. On the other hand, if kzalloc fails, it will just return in init
func. Even if static_call_key_sites(key) = true, the exit func will match
the mod before the site_mod->next = NULL node is traversed. So just
break if it the key->mods is NULL in exit func to avoid
wild-memory-access in the subsequent site traversal.

 general protection fault, probably for non-canonical address 0xeb800159c89f94a0: 0000 [#1] PREEMPT SMP KASAN
 KASAN: maybe wild-memory-access in range [0x5c002ace44fca500-0x5c002ace44fca507]
 CPU: 2 PID: 1843 Comm: modprobe Tainted: G        W        N 6.6.0-rc1+ #60
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
 RIP: 0010:static_call_del_module+0x113/0x280
 Code: 3c 20 00 0f 85 ef 00 00 00 49 8b 6e 08 48 85 ed 75 0d eb 75 48 85 db 74 70 49 89 ef 48 89 dd 48 8d 7d 08 48 89 f8 48 c1 e8 03 <42> 80 3c 20 00 75 78 48 89 e8 4c 8b 6d 08 48 c1 e8 03 42 80 3c 20
 RSP: 0018:ffff888101d3f860 EFLAGS: 00010206
 RAX: 0b800559c89f94a0 RBX: 5c002ace44fca4f8 RCX: ffffffffa0210f00
 RDX: ffffffffa0210ed4 RSI: ffffffffa0210edc RDI: 5c002ace44fca500
 RBP: 5c002ace44fca4f8 R08: 0000000000000000 R09: ffffed10233e4eea
 R10: ffffed10233e4ee9 R11: ffff888119f2774b R12: dffffc0000000000
 R13: 80002ace3cfca4f8 R14: ffffffff85196de0 R15: ffffffff84ee9f99
 FS:  00007f4ff6faa540(0000) GS:ffff888119f00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007ffc3d1f19e8 CR3: 0000000109fa6001 CR4: 0000000000170ee0
 DR0: ffffffff8faefce8 DR1: ffffffff8faefce9 DR2: ffffffff8faefcea
 DR3: ffffffff8faefceb DR6: 00000000ffff0ff0 DR7: 0000000000000600
 Call Trace:
  <TASK>
  ? __die_body+0x1b/0x60
  ? die_addr+0x43/0x70
  ? exc_general_protection+0x121/0x210
  ? asm_exc_general_protection+0x22/0x30
  ? static_call_del_module+0x113/0x280
  ? __SCT__tp_func_ipi_exit+0x8/0x8
  static_call_module_notify+0x27f/0x390
  ? rcu_segcblist_inc_len+0x17/0x20
  notifier_call_chain+0xbf/0x280
  notifier_call_chain_robust+0x7f/0xe0
  ? notifier_call_chain+0x280/0x280
  ? kasan_quarantine_put+0x46/0x160
  blocking_notifier_call_chain_robust+0x5b/0x80
  load_module+0x4d1d/0x69f0
  ? module_frob_arch_sections+0x20/0x20
  ? update_cfs_group+0x10c/0x2a0
  ? __wake_up_common+0x10b/0x5d0
  ? kernel_read_file+0x3ca/0x510
  ? __x64_sys_fsconfig+0x650/0x650
  ? __schedule+0xa0b/0x2a60
  ? init_module_from_file+0xd2/0x130
  init_module_from_file+0xd2/0x130
  ? __ia32_sys_init_module+0xa0/0xa0
  ? _raw_spin_lock_irqsave+0xe0/0xe0
  ? ptrace_stop+0x487/0x790
  idempotent_init_module+0x32d/0x6a0
  ? init_module_from_file+0x130/0x130
  ? __fget_light+0x57/0x500
  __x64_sys_finit_module+0xbb/0x130
  do_syscall_64+0x35/0x80
  entry_SYSCALL_64_after_hwframe+0x46/0xb0

Fixes: 9183c3f9ed71 ("static_call: Add inline static call infrastructure")
Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
---
v2:
- Update the fix tag.
- Remove the redundant error information.
- Update the commit message description.
---
 kernel/static_call_inline.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/static_call_inline.c b/kernel/static_call_inline.c
index 639397b5491c..e7aa70d33530 100644
--- a/kernel/static_call_inline.c
+++ b/kernel/static_call_inline.c
@@ -256,8 +256,10 @@ static int __static_call_init(struct module *mod,
 			}
 
 			site_mod = kzalloc(sizeof(*site_mod), GFP_KERNEL);
-			if (!site_mod)
+			if (!site_mod) {
+				key->mods = NULL;
 				return -ENOMEM;
+			}
 
 			/*
 			 * When the key has a direct sites pointer, extract
@@ -422,7 +424,7 @@ static void static_call_del_module(struct module *mod)
 			;
 
 		if (!site_mod)
-			continue;
+			break;
 
 		*prev = site_mod->next;
 		kfree(site_mod);
-- 
2.34.1