From 5ec850f0f15dd128c0d584234cdcade9ddf9bb0f Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 4 May 2020 18:47:25 +0200 Subject: uprobes: ensure that uprobe->offset and ->ref_ctr_offset are properly aligned 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 Suggested-by: Linus Torvalds Signed-off-by: Oleg Nesterov Reviewed-by: Srikar Dronamraju Acked-by: Christian Borntraeger Tested-by: Sven Schnelle Cc: Steven Rostedt Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds [ check for ref_ctr_offset removed for backport - gregkh ] Signed-off-by: Greg Kroah-Hartman --- kernel/events/uprobes.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 8ddd29476c0d..1fcaa174ed32 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -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(); -- cgit v1.2.3