Messages in this thread | | | Date | Tue, 16 Aug 2022 09:00:33 +0800 | Subject | Re: [PATCH] asm/sections: fix the determination of the end of the memory region | From | Quanyang Wang <> |
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Hi Ard,
On 8/11/22 16:16, Ard Biesheuvel wrote: > On Thu, 11 Aug 2022 at 08:31, <quanyang.wang@windriver.com> wrote: >> >> From: Quanyang Wang <quanyang.wang@windriver.com> >> >> If using "vend >= begin" to judge if two memory regions intersects, vend >> should be the end of the memory region, so it should be "virt + size -1" >> instead of "virt + size". >> The wrong determination of the end triggers the misreporting as below when >> the dma debug function "check_for_illegal_area" calls memory_intersects to >> check if the dma region intersects with stext region. >> >> Calltrace (stext is at 0x80100000): >> WARNING: CPU: 0 PID: 77 at kernel/dma/debug.c:1073 check_for_illegal_area+0x130/0x168 >> DMA-API: chipidea-usb2 e0002000.usb: device driver maps memory from kernel text or rodata [addr=800f0000] [len=65536] >> Modules linked in: >> CPU: 1 PID: 77 Comm: usb-storage Not tainted 5.19.0-yocto-standard #5 >> Hardware name: Xilinx Zynq Platform >> unwind_backtrace from show_stack+0x18/0x1c >> show_stack from dump_stack_lvl+0x58/0x70 >> dump_stack_lvl from __warn+0xb0/0x198 >> __warn from warn_slowpath_fmt+0x80/0xb4 >> warn_slowpath_fmt from check_for_illegal_area+0x130/0x168 >> check_for_illegal_area from debug_dma_map_sg+0x94/0x368 >> debug_dma_map_sg from __dma_map_sg_attrs+0x114/0x128 >> __dma_map_sg_attrs from dma_map_sg_attrs+0x18/0x24 >> dma_map_sg_attrs from usb_hcd_map_urb_for_dma+0x250/0x3b4 >> usb_hcd_map_urb_for_dma from usb_hcd_submit_urb+0x194/0x214 >> usb_hcd_submit_urb from usb_sg_wait+0xa4/0x118 >> usb_sg_wait from usb_stor_bulk_transfer_sglist+0xa0/0xec >> usb_stor_bulk_transfer_sglist from usb_stor_bulk_srb+0x38/0x70 >> usb_stor_bulk_srb from usb_stor_Bulk_transport+0x150/0x360 >> usb_stor_Bulk_transport from usb_stor_invoke_transport+0x38/0x440 >> usb_stor_invoke_transport from usb_stor_control_thread+0x1e0/0x238 >> usb_stor_control_thread from kthread+0xf8/0x104 >> kthread from ret_from_fork+0x14/0x2c >> >> Fixes: 979559362516 ("asm/sections: add helpers to check for section data") >> Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com> >> --- >> include/asm-generic/sections.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h >> index d0f7bdd2fdf2..f7171b4f5bfd 100644 >> --- a/include/asm-generic/sections.h >> +++ b/include/asm-generic/sections.h >> @@ -108,7 +108,7 @@ static inline bool memory_contains(void *begin, void *end, void *virt, >> static inline bool memory_intersects(void *begin, void *end, void *virt, >> size_t size) >> { >> - void *vend = virt + size; >> + void *vend = virt + size - 1; >> >> return (virt >= begin && virt < end) || (vend >= begin && vend < end); > > This test looks flawed to me for another reason as well: it only > checks whether the start /or/ the end of (virt, virt+size) falls > inside the area, so if the area is covered completely (in which case > the intersection of the two will be equal to the area), this will > return false erroneously. Yes, the test lacks some checks. I will send a V2 patch to fix it. Thanks, Quanyang
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