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authorAl Viro <viro@zeniv.linux.org.uk>2023-01-30 23:55:52 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2023-03-02 12:30:15 -0500
commitd835eb3a57de50d16dd4a6b53f95dbc2bfa8ef48 (patch)
treed027d106b51591b8d2b6eedc82b19368fc27ef93
parentbd75497a77ccae9a5e1b0f1a3fa8283d67b21f4c (diff)
riscv: fix livelock in uaccess
riscv equivalent of 26178ec11ef3 "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. Tested-by: Björn Töpel <bjorn@kernel.org> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--arch/riscv/mm/fault.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index d86f7cebd4a7..c91d85349d39 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -324,8 +324,11 @@ good_area:
* signal first. We do not need to release the mmap_lock because it
* would already be released in __lock_page_or_retry in mm/filemap.c.
*/
- if (fault_signal_pending(fault, regs))
+ if (fault_signal_pending(fault, regs)) {
+ if (!user_mode(regs))
+ no_context(regs, addr);
return;
+ }
/* The fault is fully completed (including releasing mmap lock) */
if (fault & VM_FAULT_COMPLETED)