On Sun, Aug 19, 2018 at 10:54 PM, Song Liu <liu.song....@gmail.com> wrote:
> On Sun, Aug 19, 2018 at 9:42 PM, Ravi Bangoria
> <ravi.bango...@linux.ibm.com> wrote:
>> We assume to have only one reference counter for one uprobe.
>> Don't allow user to register multiple uprobes having same
>> inode+offset but different reference counter.
>>
>> Signed-off-by: Ravi Bangoria <ravi.bango...@linux.ibm.com>
>> Acked-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
>> Reviewed-by: Oleg Nesterov <o...@redhat.com>
>
> Reviewed-by: Song Liu <songliubrav...@fb.com>
Reviewed-and-tested-by: Song Liu <songliubrav...@fb.com>
>
>> ---
>> kernel/events/uprobes.c | 19 +++++++++++++++++++
>> 1 file changed, 19 insertions(+)
>>
>> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
>> index 35065febcb6c..ecee371a59c7 100644
>> --- a/kernel/events/uprobes.c
>> +++ b/kernel/events/uprobes.c
>> @@ -679,6 +679,16 @@ static struct uprobe *insert_uprobe(struct uprobe
>> *uprobe)
>> return u;
>> }
>>
>> +static void
>> +ref_ctr_mismatch_warn(struct uprobe *cur_uprobe, struct uprobe *uprobe)
>> +{
>> + pr_warn("ref_ctr_offset mismatch. inode: 0x%lx offset: 0x%llx "
>> + "ref_ctr_offset(old): 0x%llx ref_ctr_offset(new): 0x%llx\n",
>> + uprobe->inode->i_ino, (unsigned long long) uprobe->offset,
>> + (unsigned long long) cur_uprobe->ref_ctr_offset,
>> + (unsigned long long) uprobe->ref_ctr_offset);
>> +}
>> +
>> static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset,
>> loff_t ref_ctr_offset)
>> {
>> @@ -698,6 +708,12 @@ static struct uprobe *alloc_uprobe(struct inode *inode,
>> loff_t offset,
>> cur_uprobe = insert_uprobe(uprobe);
>> /* a uprobe exists for this inode:offset combination */
>> if (cur_uprobe) {
>> + if (cur_uprobe->ref_ctr_offset != uprobe->ref_ctr_offset) {
>> + ref_ctr_mismatch_warn(cur_uprobe, uprobe);
>> + put_uprobe(cur_uprobe);
>> + kfree(uprobe);
>> + return ERR_PTR(-EINVAL);
>> + }
>> kfree(uprobe);
>> uprobe = cur_uprobe;
>> }
>> @@ -1112,6 +1128,9 @@ static int __uprobe_register(struct inode *inode,
>> loff_t offset,
>> uprobe = alloc_uprobe(inode, offset, ref_ctr_offset);
>> if (!uprobe)
>> return -ENOMEM;
>> + if (IS_ERR(uprobe))
>> + return PTR_ERR(uprobe);
>> +
>> /*
>> * We can race with uprobe_unregister()->delete_uprobe().
>> * Check uprobe_is_active() and retry if it is false.
>> --
>> 2.14.4
>>
