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| author | Oleg Nesterov <oleg@redhat.com> | 2020-05-04 18:47:25 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-09 09:49:24 -0700 |
| commit | 013b2deba9a6b80ca02f4fafd7dedf875e9b4450 (patch) | |
| tree | 5bd2542332362d7ea7e39c5243a0845515bfc789 /kernel/events/uprobes.c | |
| parent | 8b4d37db9a566deaf22065ba1ba9b19c9fb964b4 (diff) | |
| download | linux-013b2deba9a6b80ca02f4fafd7dedf875e9b4450.tar.gz linux-013b2deba9a6b80ca02f4fafd7dedf875e9b4450.tar.bz2 linux-013b2deba9a6b80ca02f4fafd7dedf875e9b4450.zip | |
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 <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>
Diffstat (limited to 'kernel/events/uprobes.c')
| -rw-r--r-- | kernel/events/uprobes.c | 16 |
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(); |