| /linux/arch/riscv/include/asm/ |
| H A D | uprobes.h | diff 9f564b92cf6d0ecb398f9348600a7d8a7f8ea804 Tue Sep 12 08:56:19 CEST 2023 Björn Töpel <bjorn@rivosinc.com> riscv: Only consider swbp/ss handlers for correct privileged mode
RISC-V software breakpoint trap handlers are used for {k,u}probes.
When trapping from kernelmode, only the kernelmode handlers should be
considered. Vice versa, only usermode handlers for usermode
traps. This is not the case on RISC-V, which can trigger a bug if a
userspace process uses uprobes, and a WARN() is triggered from
kernelmode (which is implemented via {c.,}ebreak).
The kernel will trap on the kernelmode {c.,}ebreak, look for uprobes
handlers, realize incorrectly that uprobes need to be handled, and
exit the trap handler early. The trap returns to re-executing the
{c.,}ebreak, and enter an infinite trap-loop.
The issue was found running the BPF selftest [1].
Fix this issue by only considering the swbp/ss handlers for
kernel/usermode respectively. Also, move CONFIG ifdeffery from traps.c
to the asm/{k,u}probes.h headers.
Note that linux/uprobes.h only include asm/uprobes.h if CONFIG_UPROBES
is defined, which is why asm/uprobes.h needs to be unconditionally
included in traps.c
Link: https://lore.kernel.org/linux-riscv/87v8d19aun.fsf@all.your.base.are.belong.to.us/ # [1]
Fixes: 74784081aac8 ("riscv: Add uprobes supported")
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Nam Cao <namcaov@gmail.com>
Tested-by: Puranjay Mohan <puranjay12@gmail.com>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230912065619.62020-1-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
|
| H A D | kprobes.h | diff 9f564b92cf6d0ecb398f9348600a7d8a7f8ea804 Tue Sep 12 08:56:19 CEST 2023 Björn Töpel <bjorn@rivosinc.com> riscv: Only consider swbp/ss handlers for correct privileged mode
RISC-V software breakpoint trap handlers are used for {k,u}probes.
When trapping from kernelmode, only the kernelmode handlers should be
considered. Vice versa, only usermode handlers for usermode
traps. This is not the case on RISC-V, which can trigger a bug if a
userspace process uses uprobes, and a WARN() is triggered from
kernelmode (which is implemented via {c.,}ebreak).
The kernel will trap on the kernelmode {c.,}ebreak, look for uprobes
handlers, realize incorrectly that uprobes need to be handled, and
exit the trap handler early. The trap returns to re-executing the
{c.,}ebreak, and enter an infinite trap-loop.
The issue was found running the BPF selftest [1].
Fix this issue by only considering the swbp/ss handlers for
kernel/usermode respectively. Also, move CONFIG ifdeffery from traps.c
to the asm/{k,u}probes.h headers.
Note that linux/uprobes.h only include asm/uprobes.h if CONFIG_UPROBES
is defined, which is why asm/uprobes.h needs to be unconditionally
included in traps.c
Link: https://lore.kernel.org/linux-riscv/87v8d19aun.fsf@all.your.base.are.belong.to.us/ # [1]
Fixes: 74784081aac8 ("riscv: Add uprobes supported")
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Nam Cao <namcaov@gmail.com>
Tested-by: Puranjay Mohan <puranjay12@gmail.com>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230912065619.62020-1-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
|
| /linux/arch/riscv/kernel/ |
| H A D | traps.c | diff 9f564b92cf6d0ecb398f9348600a7d8a7f8ea804 Tue Sep 12 08:56:19 CEST 2023 Björn Töpel <bjorn@rivosinc.com> riscv: Only consider swbp/ss handlers for correct privileged mode
RISC-V software breakpoint trap handlers are used for {k,u}probes.
When trapping from kernelmode, only the kernelmode handlers should be
considered. Vice versa, only usermode handlers for usermode
traps. This is not the case on RISC-V, which can trigger a bug if a
userspace process uses uprobes, and a WARN() is triggered from
kernelmode (which is implemented via {c.,}ebreak).
The kernel will trap on the kernelmode {c.,}ebreak, look for uprobes
handlers, realize incorrectly that uprobes need to be handled, and
exit the trap handler early. The trap returns to re-executing the
{c.,}ebreak, and enter an infinite trap-loop.
The issue was found running the BPF selftest [1].
Fix this issue by only considering the swbp/ss handlers for
kernel/usermode respectively. Also, move CONFIG ifdeffery from traps.c
to the asm/{k,u}probes.h headers.
Note that linux/uprobes.h only include asm/uprobes.h if CONFIG_UPROBES
is defined, which is why asm/uprobes.h needs to be unconditionally
included in traps.c
Link: https://lore.kernel.org/linux-riscv/87v8d19aun.fsf@all.your.base.are.belong.to.us/ # [1]
Fixes: 74784081aac8 ("riscv: Add uprobes supported")
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Nam Cao <namcaov@gmail.com>
Tested-by: Puranjay Mohan <puranjay12@gmail.com>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230912065619.62020-1-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
|