On Wed, Jun 10, 2020 at 12:25:56AM +0530, Naresh Kamboju wrote:
On Tue, 9 Jun 2020 at 23:35, Greg Kroah-Hartman gregkh@linuxfoundation.org wrote:
From: Oleg Nesterov oleg@redhat.com
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
kernel/events/uprobes.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)
--- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -612,10 +612,6 @@ static int prepare_uprobe(struct uprobe 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);@@ -911,6 +907,15 @@ static int __uprobe_register(struct inod 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)))stable-rc 4.19 build failure for x86_64, i386 and arm. make -sk KBUILD_BUILD_USER=TuxBuild -C/linux -j16 ARCH=x86 HOSTCC=gcc CC="sccache gcc" O=build
75 # 76 In file included from ../kernel/events/uprobes.c:25: 77 ../kernel/events/uprobes.c: In function ‘__uprobe_register’: 78 ../kernel/events/uprobes.c:916:18: error: ‘ref_ctr_offset’ undeclared (first use in this function); did you mean ‘per_cpu_offset’? 79 916 | if (!IS_ALIGNED(ref_ctr_offset, sizeof(short))) 80 | ^~~~~~~~~~~~~~ 81 ../include/linux/kernel.h:62:30: note: in definition of macro ‘IS_ALIGNED’ 82 62 | #define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0) 83 | ^ 84 ../kernel/events/uprobes.c:916:18: note: each undeclared identifier is reported only once for each function it appears in 85 916 | if (!IS_ALIGNED(ref_ctr_offset, sizeof(short))) 86 | ^~~~~~~~~~~~~~ 87 ../include/linux/kernel.h:62:30: note: in definition of macro ‘IS_ALIGNED’ 88 62 | #define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0) 89 | ^ 90 make[3]: *** [../scripts/Makefile.build:304: kernel/events/uprobes.o] Error 1
-- Linaro LKFT https://lkft.linaro.org
Good catch, my builders just caught it too :(
4.19, 4.14, 4.9, and 4.4 are all broken, I have a fix will test it and push out -rc2 for all of those with it in a bit, thanks.
greg k-h