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Wed, 19 Feb 2025 18:16:45 -0800 (PST) Message-ID: <5c5232ee-4b4d-42a1-9be9-3489f93f7590@bytedance.com> Date: Thu, 20 Feb 2025 10:16:39 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] arm: pgtable: fix NULL pointer dereference issue Content-Language: en-US To: Ezra Buehler Cc: linux@armlinux.org.uk, david@redhat.com, hughd@google.com, ryan.roberts@arm.com, akpm@linux-foundation.org, muchun.song@linux.dev, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ezra Buehler , stable@vger.kernel.org References: <20250217024924.57996-1-zhengqi.arch@bytedance.com> From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: 3usboecphecgh1e7tj887awrpmq97wb1 X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 9E1FA80006 X-Rspam-User: X-HE-Tag: 1740017807-771084 X-HE-Meta: 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 jqEpnls6 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2025/2/19 18:58, Ezra Buehler wrote: > On Mon, Feb 17, 2025 at 3:49 AM Qi Zheng wrote: >> >> When update_mmu_cache_range() is called by update_mmu_cache(), the vmf >> parameter is NULL, which will cause a NULL pointer dereference issue in >> adjust_pte(): >> >> Unable to handle kernel NULL pointer dereference at virtual address 00000030 when read >> Hardware name: Atmel AT91SAM9 >> PC is at update_mmu_cache_range+0x1e0/0x278 >> LR is at pte_offset_map_rw_nolock+0x18/0x2c >> Call trace: >> update_mmu_cache_range from remove_migration_pte+0x29c/0x2ec >> remove_migration_pte from rmap_walk_file+0xcc/0x130 >> rmap_walk_file from remove_migration_ptes+0x90/0xa4 >> remove_migration_ptes from migrate_pages_batch+0x6d4/0x858 >> migrate_pages_batch from migrate_pages+0x188/0x488 >> migrate_pages from compact_zone+0x56c/0x954 >> compact_zone from compact_node+0x90/0xf0 >> compact_node from kcompactd+0x1d4/0x204 >> kcompactd from kthread+0x120/0x12c >> kthread from ret_from_fork+0x14/0x38 >> Exception stack(0xc0d8bfb0 to 0xc0d8bff8) >> >> To fix it, do not rely on whether 'ptl' is equal to decide whether to hold >> the pte lock, but decide it by whether CONFIG_SPLIT_PTE_PTLOCKS is >> enabled. In addition, if two vmas map to the same PTE page, there is no >> need to hold the pte lock again, otherwise a deadlock will occur. Just add >> the need_lock parameter to let adjust_pte() know this information. >> >> Reported-by: Ezra Buehler >> Closes: https://lore.kernel.org/lkml/CAM1KZSmZ2T_riHvay+7cKEFxoPgeVpHkVFTzVVEQ1BO0cLkHEQ@mail.gmail.com/ >> Fixes: fc9c45b71f43 ("arm: adjust_pte() use pte_offset_map_rw_nolock()") >> Cc: stable@vger.kernel.org >> Signed-off-by: Qi Zheng >> Acked-by: David Hildenbrand > > Tested-by: Ezra Buehler > > I confirm that this fixes our issue on the AT91SAM9G25-based GARDENA > smart Gateway. > > However, unfortunately, I do not have a 4-core ARMv5 board at hand to > test the CONFIG_SPLIT_PTE_PTLOCKS case. Got it. And thank you very much for your testing! > > Cheers, > Ezra.