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kprobes/x86: Use copy_from_kernel_nofault() to read from unsafe address

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Read from an unsafe address with copy_from_kernel_nofault() in
arch_adjust_kprobe_addr() because this function is used before checking
the address is in text or not. Syzcaller bot found a bug and reported
the case if user specifies inaccessible data area,
arch_adjust_kprobe_addr() will cause a kernel panic.

[ mingo: Clarified the comment. ]

Fixes: cc66bb9145 ("x86/ibt,kprobes: Cure sym+0 equals fentry woes")
Reported-by: Qiang Zhang <zzqq0103.hey@gmail.com>
Tested-by: Jinghao Jia <jinghao7@illinois.edu>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/171042945004.154897.2221804961882915806.stgit@devnote2
This commit is contained in:
Masami Hiramatsu (Google) 2024-03-15 00:17:30 +09:00 committed by Ingo Molnar
parent e3f269ed0a
commit 4e51653d5d
1 changed files with 10 additions and 1 deletions
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11
arch/x86/kernel/kprobes/core.c
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@ -373,7 +373,16 @@ out:
kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset,
bool *on_func_entry)
{
if (is_endbr(*(u32 *)addr)) {
u32 insn;
/*
* Since 'addr' is not guaranteed to be safe to access, use
* copy_from_kernel_nofault() to read the instruction:
*/
if (copy_from_kernel_nofault(&insn, (void *)addr, sizeof(u32)))
return NULL;
if (is_endbr(insn)) {
*on_func_entry = !offset || offset == 4;
if (*on_func_entry)
offset = 4;