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@xxxxxxxxxxxxxxxxxxx> wrote: > > > > From: Oleg Nesterov <oleg@xxxxxxxxxx> > > > > 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@xxxxxxxxxxxxxxxxxxxx> > > Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > > Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> > > Reviewed-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx> > > Acked-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> > > Tested-by: Sven Schnelle <svens@xxxxxxxxxxxxx> > > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> > > Cc: stable@xxxxxxxxxxxxxxx > > Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > > > --- > > 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
