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sparc: fix livelock in uaccess 

sparc equivalent of 26178ec11e "x86: mm: consolidate VM_FAULT_RETRY handling"
If e.g. get_user() triggers a page fault and a fatal signal is caught, we might
end up with handle_mm_fault() returning VM_FAULT_RETRY and not doing anything
to page tables.  In such case we must *not* return to the faulting insn -
that would repeat the entire thing without making any progress; what we need
instead is to treat that as failed (user) memory access.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2023-01-31 00:03:40 -05:00
parent dce45493af
commit 79c54c97c7
2 changed files with 10 additions and 2 deletions
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5
arch/sparc/mm/fault_32.c
View File

@ -187,8 +187,11 @@ asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
*/
fault = handle_mm_fault(vma, address, flags, regs);
if (fault_signal_pending(fault, regs))
if (fault_signal_pending(fault, regs)) {
if (!from_user)
goto no_context;
return;
}
/* The fault is fully completed (including releasing mmap lock) */
if (fault & VM_FAULT_COMPLETED)

7
arch/sparc/mm/fault_64.c
View File

@ -424,8 +424,13 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
fault = handle_mm_fault(vma, address, flags, regs);
if (fault_signal_pending(fault, regs))
if (fault_signal_pending(fault, regs)) {
if (regs->tstate & TSTATE_PRIV) {
insn = get_fault_insn(regs, insn);
goto handle_kernel_fault;
}
goto exit_exception;
}
/* The fault is fully completed (including releasing mmap lock) */
if (fault & VM_FAULT_COMPLETED)