KASAN Arm: global-out-of-bounds in load_module

[Miguel Ojeda]

Hi KASAN / Arm folks,

I noticed in our CI that inserting and removing a module, and then
inserting it again, e.g.:

    insmod bcm2835_thermal.ko
    rmmod bcm2835_thermal.ko
    insmod bcm2835_thermal.ko

deterministically triggers the report below in v5.16-rc2. I also tried
it on v5.12 to see if it was a recent thing, but same story.

I could find this other report from May, which may be related:
https://lore.kernel.org/lkml/20210510202653.gjvqsxacw3hcxfvr@xxxxxxxxxxxxxx/

Cheers,
Miguel

BUG: KASAN: global-out-of-bounds in load_module+0x1b98/0x33b0
Write of size 16384 at addr bf000000 by task busybox/17

CPU: 0 PID: 17 Comm: busybox Not tainted 5.15.0 #7
Hardware name: Generic DT based system
[<c010f968>] (unwind_backtrace) from [<c010c6f8>] (show_stack+0x10/0x14)
[<c010c6f8>] (show_stack) from [<c0210734>]
(print_address_description+0x58/0x384)
[<c0210734>] (print_address_description) from [<c0210cc8>]
(kasan_report+0x168/0x1fc)
[<c0210cc8>] (kasan_report) from [<c0211230>] (kasan_check_range+0x260/0x2a8)
[<c0211230>] (kasan_check_range) from [<c0211c68>] (memset+0x20/0x44)
[<c0211c68>] (memset) from [<c019d21c>] (load_module+0x1b98/0x33b0)
[<c019d21c>] (load_module) from [<c0199f88>] (sys_init_module+0x198/0x1ac)
[<c0199f88>] (sys_init_module) from [<c0100060>] (ret_fast_syscall+0x0/0x48)
Exception stack(0xc113ffa8 to 0xc113fff0)
ffa0:                   00000000 00002a98 00098038 00002a98 00081483 00093f88
ffc0: 00000000 00002a98 00000000 00000080 00000001 b66ffef0 00081483 000815c7
ffe0: b66ffbd8 b66ffbc8 000207f5 00011cc2


Memory state around the buggy address:
 bf001200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 bf001280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>bf001300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f9 f9
                                                     ^
 bf001380: 00 00 07 f9 f9 f9 f9 f9 00 00 00 00 00 00 00 00
 bf001400: 00 00 f9 f9 f9 f9 f9 f9 00 00 04 f9 f9 f9 f9 f9