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uprobes: ensure that uprobe->offset and ->ref_ctr_offset are properly aligned

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commit 013b2deba9a6b80ca02f4fafd7dedf875e9b4450 upstream.

uprobe_write_opcode() must not cross page boundary; prepare_uprobe()
relies on arch_uprobe_analyze_insn() which should validate "vaddr" but
some architectures (csky, s390, and sparc) don't do this.

We can remove the BUG_ON() check in prepare_uprobe() and validate the
offset early in __uprobe_register(). The new IS_ALIGNED() check matches
the alignment check in arch_prepare_kprobe() on supported architectures,
so I think that all insns must be aligned to UPROBE_SWBP_INSN_SIZE.

Another problem is __update_ref_ctr() which was wrong from the very
beginning, it can read/write outside of kmap'ed page unless "vaddr" is
aligned to sizeof(short), __uprobe_register() should check this too.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ check for ref_ctr_offset removed for backport - gregkh ]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Oleg Nesterov 2020-05-04 18:47:25 +02:00 committed by Greg Kroah-Hartman
parent 259108a77b
commit 5ec850f0f1
1 changed files with 10 additions and 4 deletions
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14
kernel/events/uprobes.c
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@ -604,10 +604,6 @@ static int prepare_uprobe(struct uprobe *uprobe, struct file *file,
if (ret)
goto out;
/* uprobe_write_opcode() assumes we don't cross page boundary */
BUG_ON((uprobe->offset & ~PAGE_MASK) +
UPROBE_SWBP_INSN_SIZE > PAGE_SIZE);
smp_wmb(); /* pairs with the smp_rmb() in handle_swbp() */
set_bit(UPROBE_COPY_INSN, &uprobe->flags);
@ -886,6 +882,13 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *
if (offset > i_size_read(inode))
return -EINVAL;
/*
* This ensures that copy_from_page() and copy_to_page()
* can't cross page boundary.
*/
if (!IS_ALIGNED(offset, UPROBE_SWBP_INSN_SIZE))
return -EINVAL;
retry:
uprobe = alloc_uprobe(inode, offset);
if (!uprobe)
@ -1696,6 +1699,9 @@ static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr)
uprobe_opcode_t opcode;
int result;
if (WARN_ON_ONCE(!IS_ALIGNED(vaddr, UPROBE_SWBP_INSN_SIZE)))
return -EINVAL;
pagefault_disable();
result = __get_user(opcode, (uprobe_opcode_t __user *)vaddr);
pagefault_enable();