| Message ID | tencent_E036A29600368E4A2075A7774D67023CFD09@qq.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | ring-buffer: Fix a oob in __rb_map_vma | expand |
On Mon, 16 Dec 2024 22:07:57 +0800 Edward Adam Davis <eadavis@qq.com> wrote: > syzbot report a slab-out-of-bounds in __rb_map_vma. [1] > > Overflow occurred when performing the following calculation: > nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; > > Add a check before the calculation to avoid this problem. > > [1] > BUG: KASAN: slab-out-of-bounds in __rb_map_vma+0x9ab/0xae0 kernel/trace/ring_buffer.c:7058 > Read of size 8 at addr ffff8880767dd2b8 by task syz-executor187/5836 > > CPU: 0 UID: 0 PID: 5836 Comm: syz-executor187 Not tainted 6.13.0-rc2-syzkaller-00159-gf932fb9b4074 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024 > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:94 [inline] > dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 > print_address_description mm/kasan/report.c:378 [inline] > print_report+0xc3/0x620 mm/kasan/report.c:489 > kasan_report+0xd9/0x110 mm/kasan/report.c:602 > __rb_map_vma+0x9ab/0xae0 kernel/trace/ring_buffer.c:7058 > ring_buffer_map+0x56e/0x9b0 kernel/trace/ring_buffer.c:7138 > tracing_buffers_mmap+0xa6/0x120 kernel/trace/trace.c:8482 > call_mmap include/linux/fs.h:2183 [inline] > mmap_file mm/internal.h:124 [inline] > __mmap_new_file_vma mm/vma.c:2291 [inline] > __mmap_new_vma mm/vma.c:2355 [inline] > __mmap_region+0x1786/0x2670 mm/vma.c:2456 > mmap_region+0x127/0x320 mm/mmap.c:1348 > do_mmap+0xc00/0xfc0 mm/mmap.c:496 > vm_mmap_pgoff+0x1ba/0x360 mm/util.c:580 > ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:542 > __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline] > __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline] > __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Reported-by: syzbot+345e4443a21200874b18@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=345e4443a21200874b18 > Tested-by: syzbot+345e4443a21200874b18@syzkaller.appspotmail.com > Signed-off-by: Edward Adam Davis <eadavis@qq.com> > --- > kernel/trace/ring_buffer.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index 7e257e855dd1..15c43d7415d5 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -7019,6 +7019,9 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, > lockdep_assert_held(&cpu_buffer->mapping_lock); > > nr_subbufs = cpu_buffer->nr_pages + 1; /* + reader-subbuf */ > + if (((nr_subbufs + 1) << subbuf_order) < pgoff) > + return -EINVAL; > + A proper fix is being discussed here: https://lore.kernel.org/linux-trace-kernel/20241216164931.57323-1-aha310510@gmail.com/ Thank you, -- Steve > nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; /* + meta-page */ > > nr_vma_pages = vma_pages(vma);
On Tue, 17 Dec 2024 12:46:02 -0500, Steven Rostedt wrote: > On Mon, 16 Dec 2024 22:07:57 +0800 > Edward Adam Davis <eadavis@qq.com> wrote: > > > syzbot report a slab-out-of-bounds in __rb_map_vma. [1] > > > > Overflow occurred when performing the following calculation: > > nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; > > > > Add a check before the calculation to avoid this problem. > > > > [1] > > BUG: KASAN: slab-out-of-bounds in __rb_map_vma+0x9ab/0xae0 kernel/trace/ring_buffer.c:7058 > > Read of size 8 at addr ffff8880767dd2b8 by task syz-executor187/5836 > > > > CPU: 0 UID: 0 PID: 5836 Comm: syz-executor187 Not tainted 6.13.0-rc2-syzkaller-00159-gf932fb9b4074 #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024 > > Call Trace: > > <TASK> > > __dump_stack lib/dump_stack.c:94 [inline] > > dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 > > print_address_description mm/kasan/report.c:378 [inline] > > print_report+0xc3/0x620 mm/kasan/report.c:489 > > kasan_report+0xd9/0x110 mm/kasan/report.c:602 > > __rb_map_vma+0x9ab/0xae0 kernel/trace/ring_buffer.c:7058 > > ring_buffer_map+0x56e/0x9b0 kernel/trace/ring_buffer.c:7138 > > tracing_buffers_mmap+0xa6/0x120 kernel/trace/trace.c:8482 > > call_mmap include/linux/fs.h:2183 [inline] > > mmap_file mm/internal.h:124 [inline] > > __mmap_new_file_vma mm/vma.c:2291 [inline] > > __mmap_new_vma mm/vma.c:2355 [inline] > > __mmap_region+0x1786/0x2670 mm/vma.c:2456 > > mmap_region+0x127/0x320 mm/mmap.c:1348 > > do_mmap+0xc00/0xfc0 mm/mmap.c:496 > > vm_mmap_pgoff+0x1ba/0x360 mm/util.c:580 > > ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:542 > > __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline] > > __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline] > > __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82 > > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > > do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 > > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > > > Reported-by: syzbot+345e4443a21200874b18@syzkaller.appspotmail.com > > Closes: https://syzkaller.appspot.com/bug?extid=345e4443a21200874b18 > > Tested-by: syzbot+345e4443a21200874b18@syzkaller.appspotmail.com > > Signed-off-by: Edward Adam Davis <eadavis@qq.com> > > --- > > kernel/trace/ring_buffer.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > > index 7e257e855dd1..15c43d7415d5 100644 > > --- a/kernel/trace/ring_buffer.c > > +++ b/kernel/trace/ring_buffer.c > > @@ -7019,6 +7019,9 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, > > lockdep_assert_held(&cpu_buffer->mapping_lock); > > > > nr_subbufs = cpu_buffer->nr_pages + 1; /* + reader-subbuf */ > > + if (((nr_subbufs + 1) << subbuf_order) < pgoff) > > + return -EINVAL; > > + > > A proper fix is being discussed here: First, my fix is the first one. Second, the root cause of the problem is an overflow when calculating nr_pages. > > https://lore.kernel.org/linux-trace-kernel/20241216164931.57323-1-aha310510@gmail.com/ > > Thank you, > > -- Steve > The calculation of nr_pages below overflows because the pgoff value is 8, the nr_subbufs value is 3, and the subbuf_order value is 0. > > nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; /* + meta-page */ > > > > nr_vma_pages = vma_pages(vma); BR, Edward
On Wed, 18 Dec 2024 07:43:46 +0800 Edward Adam Davis <eadavis@qq.com> wrote: > > > > A proper fix is being discussed here: > First, my fix is the first one. Yes I saw that. > Second, the root cause of the problem is an overflow when calculating nr_pages. > > > > https://lore.kernel.org/linux-trace-kernel/20241216164931.57323-1-aha310510@gmail.com/ > > > > Thank you, > > > > -- Steve > > > The calculation of nr_pages below overflows because the pgoff value is 8, > the nr_subbufs value is 3, and the subbuf_order value is 0. So basically you are saying that passing in the the mmap with the pgoff is what's causing it. > > > nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; /* + meta-page */ > > > > > > nr_vma_pages = vma_pages(vma); Thanks, I believe I now have a reproducer. And yes, I'll take your patch. (If Vincent is OK with it). Here's the reproducer: ------------------------8<------------------------- #include <fcntl.h> #include <stdlib.h> #include <unistd.h> #include <asm/types.h> #include <sys/mman.h> int main(int argc, char **argv) { int page_size = getpagesize(); int fd; void *meta; system("echo 1 > /sys/kernel/tracing/buffer_size_kb"); fd = open("/sys/kernel/tracing/per_cpu/cpu0/trace_pipe_raw", O_RDONLY); meta = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, page_size * 5); } ------------------------>8------------------------- Thanks, -- Steve
> Steven Rostedt <rostedt@goodmis.org> wrote: > > On Wed, 18 Dec 2024 07:43:46 +0800 > Edward Adam Davis <eadavis@qq.com> wrote: > >>> >>> A proper fix is being discussed here: >> First, my fix is the first one. > > Yes I saw that. > >> Second, the root cause of the problem is an overflow when calculating nr_pages. >>> >>> https://lore.kernel.org/linux-trace-kernel/20241216164931.57323-1-aha310510@gmail.com/ >>> >>> Thank you, >>> >>> -- Steve >>> Oh, I did not propose a patch that fixes the root cause of this oob. My patch is a separate patch that fixes the wrong order, such as reading the array before checking the variable s with the WARN function in the loop. So I think both of these patches should be applied. Regards, Jeongjun Park >> The calculation of nr_pages below overflows because the pgoff value is 8, >> the nr_subbufs value is 3, and the subbuf_order value is 0. > > So basically you are saying that passing in the the mmap with the pgoff is > what's causing it. > >>>> nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; /* + meta-page */ >>>> >>>> nr_vma_pages = vma_pages(vma); > > > Thanks, I believe I now have a reproducer. And yes, I'll take your patch. > (If Vincent is OK with it). > > Here's the reproducer: > > ------------------------8<------------------------- > #include <fcntl.h> > #include <stdlib.h> > #include <unistd.h> > #include <asm/types.h> > #include <sys/mman.h> > > int main(int argc, char **argv) > { > int page_size = getpagesize(); > int fd; > void *meta; > > system("echo 1 > /sys/kernel/tracing/buffer_size_kb"); > fd = open("/sys/kernel/tracing/per_cpu/cpu0/trace_pipe_raw", O_RDONLY); > > meta = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, page_size * 5); > } > ------------------------>8------------------------- > > Thanks, > > > -- Steve
On Tue, Dec 17, 2024 at 07:40:15PM -0500, Steven Rostedt wrote: > On Wed, 18 Dec 2024 07:43:46 +0800 > Edward Adam Davis <eadavis@qq.com> wrote: > > > > > > > A proper fix is being discussed here: > > First, my fix is the first one. > > Yes I saw that. > > > Second, the root cause of the problem is an overflow when calculating nr_pages. > > > > > > https://lore.kernel.org/linux-trace-kernel/20241216164931.57323-1-aha310510@gmail.com/ > > > > > > Thank you, > > > > > > -- Steve > > > > > The calculation of nr_pages below overflows because the pgoff value is 8, > > the nr_subbufs value is 3, and the subbuf_order value is 0. > > So basically you are saying that passing in the the mmap with the pgoff is > what's causing it. > > > > > nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; /* + meta-page */ > > > > > > > > nr_vma_pages = vma_pages(vma); > > > Thanks, I believe I now have a reproducer. And yes, I'll take your patch. > (If Vincent is OK with it). I wanted to look at the reproducer sent by Jeongjung yesterday but got preempted. My bad. To avoid repeating the (nr_subbufs + 1) << subbuf_order How about? - nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; /* + meta-page */ + nr_pages = ((nr_subbufs + 1) << subbuf_order); /* + meta-page */ + + if (pgoff > nr_pages) + return -EINVAL; + + nr_pages -= pgoff; And probably also Fixes: 117c39200d9d ("ring-buffer: Introducing ring-buffer mapping functions") > > Here's the reproducer: > > ------------------------8<------------------------- > #include <fcntl.h> > #include <stdlib.h> > #include <unistd.h> > #include <asm/types.h> > #include <sys/mman.h> > > int main(int argc, char **argv) > { > int page_size = getpagesize(); > int fd; > void *meta; > > system("echo 1 > /sys/kernel/tracing/buffer_size_kb"); > fd = open("/sys/kernel/tracing/per_cpu/cpu0/trace_pipe_raw", O_RDONLY); > > meta = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, page_size * 5); > } > ------------------------>8------------------------- > > Thanks, > > > -- Steve
On Wed, 18 Dec 2024 09:13:43 +0000 Vincent Donnefort <vdonnefort@google.com> wrote: > And probably also > > Fixes: 117c39200d9d ("ring-buffer: Introducing ring-buffer mapping functions") I don't require patch submitters to add Fixes tags. It's more the responsibility of the maintainer to do that. I still have to validate it as there's been several times someone adds a Fixes tag which wasn't the right commit that it fixed. -- Steve
On Wed, Dec 18, 2024 at 08:19:58AM -0500, Steven Rostedt wrote: > On Wed, 18 Dec 2024 09:13:43 +0000 > Vincent Donnefort <vdonnefort@google.com> wrote: > > > And probably also > > > > Fixes: 117c39200d9d ("ring-buffer: Introducing ring-buffer mapping functions") > > I don't require patch submitters to add Fixes tags. It's more the > responsibility of the maintainer to do that. I still have to validate it as > there's been several times someone adds a Fixes tag which wasn't the right > commit that it fixed. > > -- Steve Ack. Aside, there's a selftest to check for the overflow of subbufs with the mapping... but of course it didn't test with offset > nr_subbufs. Do you think it is worth to extend it to cover this case? I'm happy to do a quick patch.
On Wed, 18 Dec 2024 14:31:31 +0000 Vincent Donnefort <vdonnefort@google.com> wrote: > Aside, there's a selftest to check for the overflow of subbufs with the > mapping... but of course it didn't test with offset > nr_subbufs. > > Do you think it is worth to extend it to cover this case? I'm happy to do a > quick patch. Yes, it should check that case. Thanks, -- Steve
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 7e257e855dd1..15c43d7415d5 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -7019,6 +7019,9 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, lockdep_assert_held(&cpu_buffer->mapping_lock); nr_subbufs = cpu_buffer->nr_pages + 1; /* + reader-subbuf */ + if (((nr_subbufs + 1) << subbuf_order) < pgoff) + return -EINVAL; + nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; /* + meta-page */ nr_vma_pages = vma_pages(vma);