Hi Nam,
I reported a riscv kprobe bug of linux-6.6.y. It seems that 03753bfacbc6(riscv: kprobes: Fix incorrect address calculation) should be reverted. There are a lot of changes of riscv kprobe in upstream. I'm not all in sure of my suggested fix. Will you kind to help?
Thanks, laokz
On 4/25/2025 4:07 PM, Greg Kroah-Hartman wrote:
On Fri, Apr 25, 2025 at 04:03:41PM +0800, Kai Zhang wrote:
On 4/22/2025 4:46 PM, Greg Kroah-Hartman wrote:
On Tue, Apr 22, 2025 at 10:58:42AM +0800, Kai Zhang wrote:
In most recent linux-6.6.y tree, `arch/riscv/kernel/probes/kprobes.c::arch_prepare_ss_slot` still has the obsolete code:
u32 insn = __BUG_INSN_32; unsigned long offset = GET_INSN_LENGTH(p->opcode); p->ainsn.api.restore = (unsigned long)p->addr + offset; patch_text_nosync(p->ainsn.api.insn, &p->opcode, 1); patch_text_nosync((void *)p->ainsn.api.insn + offset, &insn, 1);The last two 1s are wrong size of written instructions , which would lead to kernel crash, like `insmod kprobe_example.ko` gives:
[ 509.812815][ T2734] kprobe_init: Planted kprobe at 00000000c5c46130 [ 509.837606][ C5] handler_pre: <kernel_clone> p->addr = 0x00000000c5c46130, pc = 0xffffffff80032ee2, status = 0x200000120 [ 509.839315][ C5] Oops - illegal instruction [#1]
I've tried two patchs from torvalds tree and it didn't crash again:
51781ce8f448 riscv: Pass patch_text() the length in bytes (rebased) 13134cc94914 riscv: kprobes: Fix incorrect address calculation
Neither of these apply cleanly. Please provide working backports if you wish to see them added to the tree.
thanks,
greg k-h
revert 03753bfacbc6 apply 51781ce8f448 apply 13134cc94914
Thanks, but that's not how we take patches for the stable tree. Please submit these all in a tested patch series and we will be glad to queue them up.
greg k-h