From: Liao Chang <liaochang1@xxxxxxxxxx>
[ Upstream commit ca0254998be4d74cf6add70ccfab0d2dbd362a10 ]
Set kprobe at 'jalr 1140(ra)' of vfs_write results in the following
crash:
[ 32.092235] Unable to handle kernel access to user memory without uaccess routines at virtual address 00aaaaaad77b1170
[ 32.093115] Oops [#1]
[ 32.093251] Modules linked in:
[ 32.093626] CPU: 0 PID: 135 Comm: ftracetest Not tainted 6.2.0-rc2-00013-gb0aa5e5df0cb-dirty #16
[ 32.093985] Hardware name: riscv-virtio,qemu (DT)
[ 32.094280] epc : ksys_read+0x88/0xd6
[ 32.094855] ra : ksys_read+0xc0/0xd6
[ 32.095016] epc : ffffffff801cda80 ra : ffffffff801cdab8 sp : ff20000000d7bdc0
[ 32.095227] gp : ffffffff80f14000 tp : ff60000080f9cb40 t0 : ffffffff80f13e80
[ 32.095500] t1 : ffffffff8000c29c t2 : ffffffff800dbc54 s0 : ff20000000d7be60
[ 32.095716] s1 : 0000000000000000 a0 : ffffffff805a64ae a1 : ffffffff80a83708
[ 32.095921] a2 : ffffffff80f160a0 a3 : 0000000000000000 a4 : f229b0afdb165300
[ 32.096171] a5 : f229b0afdb165300 a6 : ffffffff80eeebd0 a7 : 00000000000003ff
[ 32.096411] s2 : ff6000007ff76800 s3 : fffffffffffffff7 s4 : 00aaaaaad77b1170
[ 32.096638] s5 : ffffffff80f160a0 s6 : ff6000007ff76800 s7 : 0000000000000030
[ 32.096865] s8 : 00ffffffc3d97be0 s9 : 0000000000000007 s10: 00aaaaaad77c9410
[ 32.097092] s11: 0000000000000000 t3 : ffffffff80f13e48 t4 : ffffffff8000c29c
[ 32.097317] t5 : ffffffff8000c29c t6 : ffffffff800dbc54
[ 32.097505] status: 0000000200000120 badaddr: 00aaaaaad77b1170 cause: 000000000000000d
[ 32.098011] [<ffffffff801cdb72>] ksys_write+0x6c/0xd6
[ 32.098222] [<ffffffff801cdc06>] sys_write+0x2a/0x38
[ 32.098405] [<ffffffff80003c76>] ret_from_syscall+0x0/0x2
Since the rs1 and rd might be the same one, such as 'jalr 1140(ra)',
hence it requires obtaining the target address from rs1 followed by
updating rd.
Fixes: c22b0bcb1dd0 ("riscv: Add kprobes supported")
Signed-off-by: Liao Chang <liaochang1@xxxxxxxxxx>
Reviewed-by: Guo Ren <guoren@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230116064342.2092136-1-liaochang1@xxxxxxxxxx
[Palmer: Pick Guo's cleanup]
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/riscv/kernel/probes/simulate-insn.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/riscv/kernel/probes/simulate-insn.c b/arch/riscv/kernel/probes/simulate-insn.c
index d73e96f6ed7c..a20568bd1f1a 100644
--- a/arch/riscv/kernel/probes/simulate-insn.c
+++ b/arch/riscv/kernel/probes/simulate-insn.c
@@ -71,11 +71,11 @@ bool __kprobes simulate_jalr(u32 opcode, unsigned long addr, struct pt_regs *reg
u32 rd_index = (opcode >> 7) & 0x1f;
u32 rs1_index = (opcode >> 15) & 0x1f;
- ret = rv_insn_reg_set_val(regs, rd_index, addr + 4);
+ ret = rv_insn_reg_get_val(regs, rs1_index, &base_addr);
if (!ret)
return ret;
- ret = rv_insn_reg_get_val(regs, rs1_index, &base_addr);
+ ret = rv_insn_reg_set_val(regs, rd_index, addr + 4);
if (!ret)
return ret;
--
2.39.0
