arch/riscv/kernel/signal.c:130 __restore_v_state() warn: maybe return -EFAULT instead of the bytes remaining?

BCC: [email protected]
CC: [email protected]
CC: [email protected]
TO: Andy Chiu <[email protected]>
CC: Paul Walmsley <[email protected]>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   94515f3a7d4256a5062176b7d6ed0471938cd51a
commit: 818d78ba1b3f88d2bfee249f25020211488a26c3 riscv: signal: abstract header saving for setup_sigcontext
date:   7 months ago
:::::: branch date: 16 hours ago
:::::: commit date: 7 months ago
config: riscv-randconfig-r072-20260718 (https://download.01.org/0day-ci/archive/20260718/[email protected]/config)
compiler: clang version 24.0.0git (https://github.com/llvm/llvm-project 5c0dfced1adc55429e32b1db08570abd3a219d85)
smatch: v0.5.0-9185-gbcc58b9c

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Fixes: 818d78ba1b3f ("riscv: signal: abstract header saving for setup_sigcontext")
| Reported-by: kernel test robot <[email protected]>
| Reported-by: Dan Carpenter <[email protected]>
| Closes: https://lore.kernel.org/r/[email protected]/

New smatch warnings:
arch/riscv/kernel/signal.c:130 __restore_v_state() warn: maybe return -EFAULT instead of the bytes remaining?

Old smatch warnings:
arch/riscv/kernel/signal.c:140 __restore_v_state() warn: maybe return -EFAULT instead of the bytes remaining?
arch/riscv/kernel/signal.c:166 restore_sigcontext() warn: maybe return -EFAULT instead of the bytes remaining?

vim +130 arch/riscv/kernel/signal.c

8ee0b41898fa26 Greentime Hu 2023-06-05  107  
8ee0b41898fa26 Greentime Hu 2023-06-05  108  /*
8ee0b41898fa26 Greentime Hu 2023-06-05  109   * Restore Vector extension context from the user's signal frame. This function
8ee0b41898fa26 Greentime Hu 2023-06-05  110   * assumes a valid extension header. So magic and size checking must be done by
8ee0b41898fa26 Greentime Hu 2023-06-05  111   * the caller.
8ee0b41898fa26 Greentime Hu 2023-06-05  112   */
8ee0b41898fa26 Greentime Hu 2023-06-05  113  static long __restore_v_state(struct pt_regs *regs, void __user *sc_vec)
8ee0b41898fa26 Greentime Hu 2023-06-05  114  {
8ee0b41898fa26 Greentime Hu 2023-06-05  115  	long err;
8ee0b41898fa26 Greentime Hu 2023-06-05  116  	struct __sc_riscv_v_state __user *state = sc_vec;
8ee0b41898fa26 Greentime Hu 2023-06-05  117  	void __user *datap;
8ee0b41898fa26 Greentime Hu 2023-06-05  118  
c27fa53b858b4e Björn Töpel  2024-04-03  119  	/*
c27fa53b858b4e Björn Töpel  2024-04-03  120  	 * Mark the vstate as clean prior performing the actual copy,
c27fa53b858b4e Björn Töpel  2024-04-03  121  	 * to avoid getting the vstate incorrectly clobbered by the
c27fa53b858b4e Björn Töpel  2024-04-03  122  	 *  discarded vector state.
c27fa53b858b4e Björn Töpel  2024-04-03  123  	 */
c27fa53b858b4e Björn Töpel  2024-04-03  124  	riscv_v_vstate_set_restore(current, regs);
c27fa53b858b4e Björn Töpel  2024-04-03  125  
8ee0b41898fa26 Greentime Hu 2023-06-05  126  	/* Copy everything of __sc_riscv_v_state except datap. */
8ee0b41898fa26 Greentime Hu 2023-06-05  127  	err = __copy_from_user(&current->thread.vstate, &state->v_state,
8ee0b41898fa26 Greentime Hu 2023-06-05  128  			       offsetof(struct __riscv_v_ext_state, datap));
8ee0b41898fa26 Greentime Hu 2023-06-05  129  	if (unlikely(err))
8ee0b41898fa26 Greentime Hu 2023-06-05 @130  		return err;
8ee0b41898fa26 Greentime Hu 2023-06-05  131  
8ee0b41898fa26 Greentime Hu 2023-06-05  132  	/* Copy the pointer datap itself. */
8ee0b41898fa26 Greentime Hu 2023-06-05  133  	err = __get_user(datap, &state->v_state.datap);
8ee0b41898fa26 Greentime Hu 2023-06-05  134  	if (unlikely(err))
8ee0b41898fa26 Greentime Hu 2023-06-05  135  		return err;
8ee0b41898fa26 Greentime Hu 2023-06-05  136  	/*
8ee0b41898fa26 Greentime Hu 2023-06-05  137  	 * Copy the whole vector content from user space datap. Use
8ee0b41898fa26 Greentime Hu 2023-06-05  138  	 * copy_from_user to prevent information leak.
8ee0b41898fa26 Greentime Hu 2023-06-05  139  	 */
c27fa53b858b4e Björn Töpel  2024-04-03  140  	return copy_from_user(current->thread.vstate.datap, datap, riscv_v_vsize);
8ee0b41898fa26 Greentime Hu 2023-06-05  141  }
818d78ba1b3f88 Andy Chiu    2025-11-12  142  

:::::: The code at line 130 was first introduced by commit
:::::: 8ee0b41898fa26f66e32237f179b6989c65600d6 riscv: signal: Add sigcontext save/restore for vector

:::::: TO: Greentime Hu <[email protected]>
:::::: CC: Palmer Dabbelt <[email protected]>

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