Messages in this thread | | | Date | Mon, 27 Nov 2023 12:02:27 +0000 | Subject | Re: [PATCH v2] riscv: fix incorrect use of __user pointer | From | Ben Dooks <> |
| |
On 24/11/2023 11:38, Clément Léger wrote: > These warnings were reported by sparse and were due to lack of __user > annotation as well as dereferencing such pointer: > > arch/riscv/kernel/traps_misaligned.c:361:21: warning: dereference of noderef expression > arch/riscv/kernel/traps_misaligned.c:373:21: warning: dereference of noderef expression > arch/riscv/kernel/traps_misaligned.c:381:21: warning: dereference of noderef expression > arch/riscv/kernel/traps_misaligned.c:322:24: warning: incorrect type in initializer (different address spaces) > arch/riscv/kernel/traps_misaligned.c:322:24: expected unsigned char const [noderef] __user *__gu_ptr > arch/riscv/kernel/traps_misaligned.c:322:24: got unsigned char const [usertype] *addr > arch/riscv/kernel/traps_misaligned.c:361:21: warning: dereference of noderef expression > arch/riscv/kernel/traps_misaligned.c:373:21: warning: dereference of noderef expression > arch/riscv/kernel/traps_misaligned.c:381:21: warning: dereference of noderef expression > arch/riscv/kernel/traps_misaligned.c:332:24: warning: incorrect type in initializer (different address spaces) > arch/riscv/kernel/traps_misaligned.c:332:24: expected unsigned char [noderef] __user *__gu_ptr > arch/riscv/kernel/traps_misaligned.c:332:24: got unsigned char [usertype] *addr > > As suggested by Christoph Hellwig, casting pointers from an address > space to another is not a good idea and we should rather cast the > untyped unsigned long to their final address space. Fix the ones in > load_u8()/store_u8()/__read_insn() by passing a unsigned long and then > casting it to the appropriate type (__user of not) depending if used in > kernel/ user mode. Also remove unneeded else construct in store_u8()/ > load_u8(). > > Reported-by: kernel test robot <lkp@intel.com> > Closes: https://lore.kernel.org/oe-kbuild-all/202311160606.obGOOwB3-lkp@intel.com/ > Signed-off-by: Clément Léger <cleger@rivosinc.com> > --- > arch/riscv/kernel/traps_misaligned.c | 55 +++++++++++++--------------- > 1 file changed, 25 insertions(+), 30 deletions(-) > > diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c > index 5eba37147caa..a92b88af855a 100644 > --- a/arch/riscv/kernel/traps_misaligned.c > +++ b/arch/riscv/kernel/traps_misaligned.c > @@ -265,19 +265,19 @@ static unsigned long get_f32_rs(unsigned long insn, u8 fp_reg_offset, > #define GET_F32_RS2S(insn, regs) (get_f32_rs(RVC_RS2S(insn), 0, regs)) > > #ifdef CONFIG_RISCV_M_MODE > -static inline int load_u8(struct pt_regs *regs, const u8 *addr, u8 *r_val) > +static inline int load_u8(struct pt_regs *regs, const unsigned long addr, u8 *r_val) > { > u8 val; > > - asm volatile("lbu %0, %1" : "=&r" (val) : "m" (*addr)); > + asm volatile("lbu %0, %1" : "=&r" (val) : "m" (*(const u8 *)addr)); > *r_val = val; > > return 0; > } > > -static inline int store_u8(struct pt_regs *regs, u8 *addr, u8 val) > +static inline int store_u8(struct pt_regs *regs, unsigned long addr, u8 val) > { > - asm volatile ("sb %0, %1\n" : : "r" (val), "m" (*addr)); > + asm volatile ("sb %0, %1\n" : : "r" (val), "m" (*(u8 *)addr)); > > return 0; > } > @@ -316,34 +316,32 @@ static inline int get_insn(struct pt_regs *regs, ulong mepc, ulong *r_insn) > return 0; > } > #else > -static inline int load_u8(struct pt_regs *regs, const u8 *addr, u8 *r_val) > +static inline int load_u8(struct pt_regs *regs, const unsigned long addr, u8 *r_val) > { > - if (user_mode(regs)) { > - return __get_user(*r_val, addr); > - } else { > - *r_val = *addr; > - return 0; > - } > + if (user_mode(regs)) > + return __get_user(*r_val, (u8 __user *)addr); > + > + *r_val = *(const u8 *)addr; > + return 0; > } > > -static inline int store_u8(struct pt_regs *regs, u8 *addr, u8 val) > +static inline int store_u8(struct pt_regs *regs, unsigned long addr, u8 val) > { > - if (user_mode(regs)) { > - return __put_user(val, addr); > - } else { > - *addr = val; > - return 0; > - } > + if (user_mode(regs)) > + return __put_user(val, (u8 __user *)addr); > + > + *(u8 *)addr = val; > + return 0; > } > > -#define __read_insn(regs, insn, insn_addr) \ > +#define __read_insn(regs, insn, insn_addr, type) \ > ({ \ > int __ret; \ > \ > if (user_mode(regs)) { \ > - __ret = __get_user(insn, insn_addr); \ > + __ret = __get_user(insn, (type __user *) insn_addr); \ > } else { \ > - insn = *insn_addr; \ > + insn = *(type *)insn_addr; \ > __ret = 0; \ > } \ > \ > @@ -356,9 +354,8 @@ static inline int get_insn(struct pt_regs *regs, ulong epc, ulong *r_insn) > > if (epc & 0x2) { > ulong tmp = 0; > - u16 __user *insn_addr = (u16 __user *)epc; > > - if (__read_insn(regs, insn, insn_addr)) > + if (__read_insn(regs, insn, epc, u16)) > return -EFAULT; > /* __get_user() uses regular "lw" which sign extend the loaded > * value make sure to clear higher order bits in case we "or" it > @@ -369,16 +366,14 @@ static inline int get_insn(struct pt_regs *regs, ulong epc, ulong *r_insn) > *r_insn = insn; > return 0; > } > - insn_addr++; > - if (__read_insn(regs, tmp, insn_addr)) > + epc += sizeof(u16); > + if (__read_insn(regs, tmp, epc, u16)) > return -EFAULT; > *r_insn = (tmp << 16) | insn; > > return 0; > } else { > - u32 __user *insn_addr = (u32 __user *)epc; > - > - if (__read_insn(regs, insn, insn_addr)) > + if (__read_insn(regs, insn, epc, u32)) > return -EFAULT; > if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) { > *r_insn = insn; > @@ -491,7 +486,7 @@ int handle_misaligned_load(struct pt_regs *regs) > > val.data_u64 = 0; > for (i = 0; i < len; i++) { > - if (load_u8(regs, (void *)(addr + i), &val.data_bytes[i])) > + if (load_u8(regs, addr + i, &val.data_bytes[i])) > return -1; > } > > @@ -589,7 +584,7 @@ int handle_misaligned_store(struct pt_regs *regs) > return -EOPNOTSUPP; > > for (i = 0; i < len; i++) { > - if (store_u8(regs, (void *)(addr + i), val.data_bytes[i])) > + if (store_u8(regs, addr + i, val.data_bytes[i])) >
Would it not be easier to have a switch here for memcpy or copy_to_user?
return -1; > } >
-- Ben Dooks http://www.codethink.co.uk/ Senior Engineer Codethink - Providing Genius
https://www.codethink.co.uk/privacy.html
| |