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Commit 22bad382 authored by Ravi Bangoria's avatar Ravi Bangoria Committed by Steven Rostedt (VMware)
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uprobes/sdt: Prevent multiple reference counter for same uprobe 

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.

Link: http://lkml.kernel.org/r/20180820044250.11659-3-ravi.bangoria@linux.ibm.com



Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: default avatarOleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarSong Liu <songliubraving@fb.com>
Tested-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarRavi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 1cc33161

kernel/events/uprobes.c

+19 −0
Original line number Diff line number Diff line
@@ -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.