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authorOleg Nesterov <[email protected]>2020-05-04 18:47:25 +0200
committerLinus Torvalds <[email protected]>2020-06-09 09:49:24 -0700
commit013b2deba9a6b80ca02f4fafd7dedf875e9b4450 (patch)
tree5bd2542332362d7ea7e39c5243a0845515bfc789
parent8b4d37db9a566deaf22065ba1ba9b19c9fb964b4 (diff)
uprobes: ensure that uprobe->offset and ->ref_ctr_offset are properly aligned
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 <[email protected]> Suggested-by: Linus Torvalds <[email protected]> Signed-off-by: Oleg Nesterov <[email protected]> Reviewed-by: Srikar Dronamraju <[email protected]> Acked-by: Christian Borntraeger <[email protected]> Tested-by: Sven Schnelle <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: [email protected] Signed-off-by: Linus Torvalds <[email protected]>
-rw-r--r--kernel/events/uprobes.c16
1 files changed, 12 insertions, 4 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index e51ec844c87c..5dc2f46f38c0 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -861,10 +861,6 @@ 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);
@@ -1160,6 +1156,15 @@ static int __uprobe_register(struct inode *inode, loff_t offset,
if (offset > i_size_read(inode))
return -EINVAL;
+ /*
+ * This ensures that copy_from_page(), copy_to_page() and
+ * __update_ref_ctr() can't cross page boundary.
+ */
+ if (!IS_ALIGNED(offset, UPROBE_SWBP_INSN_SIZE))
+ return -EINVAL;
+ if (!IS_ALIGNED(ref_ctr_offset, sizeof(short)))
+ return -EINVAL;
+
retry:
uprobe = alloc_uprobe(inode, offset, ref_ctr_offset);
if (!uprobe)
@@ -2008,6 +2013,9 @@ 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();