From: Quanyang Wang quanyang.wang@windriver.com
commit 0c7d7cc2b4fe2e74ef8728f030f0f1674f9f6aee upstream.
There are two problems with the current code of memory_intersects:
First, it doesn't check whether the region (begin, end) falls inside the region (virt, vend), that is (virt < begin && vend > end).
The second problem is if vend is equal to begin, it will return true but this is wrong since vend (virt + size) is not the last address of the memory region but (virt + size -1) is. The wrong determination will trigger the misreporting when the function check_for_illegal_area calls memory_intersects to check if the dma region intersects with stext region.
The misreporting is as below (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
Refactor memory_intersects to fix the two problems above.
Before the 1d7db834a027e ("dma-debug: use memory_intersects() directly"), memory_intersects is called only by printk_late_init:
printk_late_init -> init_section_intersects ->memory_intersects.
There were few places where memory_intersects was called.
When commit 1d7db834a027e ("dma-debug: use memory_intersects() directly") was merged and CONFIG_DMA_API_DEBUG is enabled, the DMA subsystem uses it to check for an illegal area and the calltrace above is triggered.
[akpm@linux-foundation.org: fix nearby comment typo] Link: https://lkml.kernel.org/r/20220819081145.948016-1-quanyang.wang@windriver.co... Fixes: 979559362516 ("asm/sections: add helpers to check for section data") Signed-off-by: Quanyang Wang quanyang.wang@windriver.com Cc: Ard Biesheuvel ardb@kernel.org Cc: Arnd Bergmann arnd@arndb.de Cc: Thierry Reding treding@nvidia.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/asm-generic/sections.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
--- a/include/asm-generic/sections.h +++ b/include/asm-generic/sections.h @@ -114,7 +114,7 @@ static inline bool memory_contains(void /** * memory_intersects - checks if the region occupied by an object intersects * with another memory region - * @begin: virtual address of the beginning of the memory regien + * @begin: virtual address of the beginning of the memory region * @end: virtual address of the end of the memory region * @virt: virtual address of the memory object * @size: size of the memory object @@ -127,7 +127,10 @@ static inline bool memory_intersects(voi { void *vend = virt + size;
- return (virt >= begin && virt < end) || (vend >= begin && vend < end); + if (virt < end && vend > begin) + return true; + + return false; }
/**