This is a note to let you know that I've just added the patch titled
xdp: Fix zero-size allocation warning in xskq_create()
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xdp-fix-zero-size-allocation-warning-in-xskq_create.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c8af6ed533380cc8e936ad6847b1c057fdd2c560
Author: Andrew Kanner <andrew.kanner@xxxxxxxxx>
Date: Sat Oct 7 10:51:49 2023 +0300
xdp: Fix zero-size allocation warning in xskq_create()
[ Upstream commit a12bbb3cccf03b12847de0f7a6772127f90936ac ]
Syzkaller reported the following issue:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 2807 at mm/vmalloc.c:3247 __vmalloc_node_range (mm/vmalloc.c:3361)
Modules linked in:
CPU: 0 PID: 2807 Comm: repro Not tainted 6.6.0-rc2+ #12
Hardware name: Generic DT based system
unwind_backtrace from show_stack (arch/arm/kernel/traps.c:258)
show_stack from dump_stack_lvl (lib/dump_stack.c:107 (discriminator 1))
dump_stack_lvl from __warn (kernel/panic.c:633 kernel/panic.c:680)
__warn from warn_slowpath_fmt (./include/linux/context_tracking.h:153 kernel/panic.c:700)
warn_slowpath_fmt from __vmalloc_node_range (mm/vmalloc.c:3361 (discriminator 3))
__vmalloc_node_range from vmalloc_user (mm/vmalloc.c:3478)
vmalloc_user from xskq_create (net/xdp/xsk_queue.c:40)
xskq_create from xsk_setsockopt (net/xdp/xsk.c:953 net/xdp/xsk.c:1286)
xsk_setsockopt from __sys_setsockopt (net/socket.c:2308)
__sys_setsockopt from ret_fast_syscall (arch/arm/kernel/entry-common.S:68)
xskq_get_ring_size() uses struct_size() macro to safely calculate the
size of struct xsk_queue and q->nentries of desc members. But the
syzkaller repro was able to set q->nentries with the value initially
taken from copy_from_sockptr() high enough to return SIZE_MAX by
struct_size(). The next PAGE_ALIGN(size) is such case will overflow
the size_t value and set it to 0. This will trigger WARN_ON_ONCE in
vmalloc_user() -> __vmalloc_node_range().
The issue is reproducible on 32-bit arm kernel.
Fixes: 9f78bf330a66 ("xsk: support use vaddr as ring")
Reported-by: syzbot+fae676d3cf469331fc89@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/all/000000000000c84b4705fb31741e@xxxxxxxxxx/T/
Reported-by: syzbot+b132693e925cbbd89e26@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/all/000000000000e20df20606ebab4f@xxxxxxxxxx/T/
Signed-off-by: Andrew Kanner <andrew.kanner@xxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Tested-by: syzbot+fae676d3cf469331fc89@xxxxxxxxxxxxxxxxxxxxxxxxx
Acked-by: Magnus Karlsson <magnus.karlsson@xxxxxxxxx>
Link: https://syzkaller.appspot.com/bug?extid=fae676d3cf469331fc89
Link: https://lore.kernel.org/bpf/20231007075148.1759-1-andrew.kanner@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/xdp/xsk_queue.c b/net/xdp/xsk_queue.c
index f8905400ee07a..d2c2640300171 100644
--- a/net/xdp/xsk_queue.c
+++ b/net/xdp/xsk_queue.c
@@ -34,6 +34,16 @@ struct xsk_queue *xskq_create(u32 nentries, bool umem_queue)
q->ring_mask = nentries - 1;
size = xskq_get_ring_size(q, umem_queue);
+
+ /* size which is overflowing or close to SIZE_MAX will become 0 in
+ * PAGE_ALIGN(), checking SIZE_MAX is enough due to the previous
+ * is_power_of_2(), the rest will be handled by vmalloc_user()
+ */
+ if (unlikely(size == SIZE_MAX)) {
+ kfree(q);
+ return NULL;
+ }
+
size = PAGE_ALIGN(size);
q->ring = vmalloc_user(size);
