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[125.236.136.221]) by smtp.gmail.com with ESMTPSA id mg3-20020a170903348300b001d91b617718sm2360050plb.98.2024.02.06.13.11.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Feb 2024 13:11:28 -0800 (PST) Received: by xplor.waratah.dyndns.org (Postfix, from userid 1000) id 59652360444; Wed, 7 Feb 2024 10:11:24 +1300 (NZDT) From: Michael Schmitz To: linux-m68k@vger.kernel.org Cc: geert@linux-m68k.org, uli@fpond.eu, fthain@linux-m68k.org, viro@zeniv.linux.org.uk, cip-dev@lists.cip-project.org, Michael Schmitz Subject: [PATCH v3 7/8] m68k: fix livelock in uaccess Date: Wed, 7 Feb 2024 10:11:03 +1300 Message-Id: <20240206211104.26421-8-schmitzmic@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20240206211104.26421-1-schmitzmic@gmail.com> References: <20240206211104.26421-1-schmitzmic@gmail.com> Precedence: bulk X-Mailing-List: linux-m68k@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: From: Al Viro commit bd75497a77ccae9a5e1b0f1a3fa8283d67b21f4c upstream. m68k 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: Finn Thain Tested-by: Geert Uytterhoeven Acked-by: Geert Uytterhoeven Signed-off-by: Al Viro [MSch: v4.4 backport compile errors fixes] Cc: # 4.4 Signed-off-by: Michael Schmitz --- arch/m68k/mm/fault.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c index 6a94cdd0c830..f94df64c3784 100644 --- a/arch/m68k/mm/fault.c +++ b/arch/m68k/mm/fault.c @@ -139,8 +139,11 @@ good_area: fault = handle_mm_fault(mm, vma, address, flags); pr_debug("handle_mm_fault returns %d\n", fault); - if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) { + if (!user_mode(regs)) + goto no_context; return 0; + } if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) -- 2.17.1