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([143.248.136.81]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82ca85eeea8sm10126828b3a.41.2026.03.31.05.19.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Mar 2026 05:19:12 -0700 (PDT) From: Sechang Lim To: Andrew Morton , "Liam R . Howlett" , Lorenzo Stoakes Cc: Vlastimil Babka , Jann Horn , Pedro Falcato , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sechang Lim Subject: [PATCH] mm/vma: fix memory leak in __mmap_region() Date: Tue, 31 Mar 2026 12:19:06 +0000 Message-ID: <20260331121906.1301155-1-rhkrqnwk98@gmail.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 6E58540017 X-Stat-Signature: h4smea9cbgfghegqi99t983pbnjkuom4 X-Rspam-User: X-HE-Tag: 1774959554-192065 X-HE-Meta: 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 KElaitf4 fHtV4tLBe6pOqjGLGV4HltsgmzK0FLmG15byaq2vHPFJ9gHVbA/OUwL3E1mf9owmjZ7noVgNa+mf0sJcP2PLJv2mEMKSzkXpb0saO8DTVxm79EIz9Nf3ww4NxGORrMmXddE3gFmre/P2C1bNIbziycW+Pikp2dTZUKTwAxS0Td9LrgJPYehYk1ni8F1w+hLEPDhyLFqile+D4obPsaTqNxdQIH5j9ZD48UCA9f3P5pYmMQKTGjWRPxsG+bi1OK1TahmmnPT56FCRQF4DEKSse1BXxiCbrtqJ6Ccrf/8DHfU19iVQSi4IDLSkYcZ1+WEj34JiK6ctuhoDtrkrT8AqMfDVMYj8tCDalOYE/CjpPg/GePFAMZKx+iJmETyC+qFwxOv5SKh1t8AlY39q1z+fAhIPXKpace+sZYWOUlctMjNroPV2YxYrqYIuPKW+98GW7/mwKCnJrx2Zh43pu7UI57BMlGuIU0dY5/n/YiwvNnCiCXqk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: commit 605f6586ecf7 ("mm/vma: do not leak memory when .mmap_prepare swaps the file") handled the success path by skipping get_file() via file_doesnt_need_get, but missed the error path. When /dev/zero is mmap'd with MAP_SHARED, mmap_zero_prepare() calls shmem_zero_setup_desc() which allocates a new shmem file to back the mapping. If __mmap_new_vma() subsequently fails, this replacement file is never fput()'d - the original is released by ksys_mmap_pgoff(), but nobody releases the new one. Add fput() for the swapped file in the error path. Reproducible with fault injection. FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 1 CPU: 2 UID: 0 PID: 366 Comm: syz.7.14 Not tainted 7.0.0-rc6 #2 PREEMPT(full) Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: dump_stack_lvl+0x164/0x1f0 should_fail_ex+0x525/0x650 should_failslab+0xdf/0x140 kmem_cache_alloc_noprof+0x78/0x630 vm_area_alloc+0x24/0x160 __mmap_region+0xf6b/0x2660 mmap_region+0x2eb/0x3a0 do_mmap+0xc79/0x1240 vm_mmap_pgoff+0x252/0x4c0 ksys_mmap_pgoff+0xf8/0x120 __x64_sys_mmap+0x12a/0x190 do_syscall_64+0xa9/0x580 entry_SYSCALL_64_after_hwframe+0x76/0x7e kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak) BUG: memory leak unreferenced object 0xffff8881118aca80 (size 360): comm "syz.7.14", pid 366, jiffies 4294913255 hex dump (first 32 bytes): 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... ff ff ff ff ff ff ff ff c0 28 4d ae ff ff ff ff .........(M..... backtrace (crc db0f53bc): kmem_cache_alloc_noprof+0x3ab/0x630 alloc_empty_file+0x5a/0x1e0 alloc_file_pseudo+0x135/0x220 __shmem_file_setup+0x274/0x420 shmem_zero_setup_desc+0x9c/0x170 mmap_zero_prepare+0x123/0x140 __mmap_region+0xdda/0x2660 mmap_region+0x2eb/0x3a0 do_mmap+0xc79/0x1240 vm_mmap_pgoff+0x252/0x4c0 ksys_mmap_pgoff+0xf8/0x120 __x64_sys_mmap+0x12a/0x190 do_syscall_64+0xa9/0x580 entry_SYSCALL_64_after_hwframe+0x76/0x7e Found by syzkaller. Fixes: 605f6586ecf7 ("mm/vma: do not leak memory when .mmap_prepare swaps the file") Signed-off-by: Sechang Lim --- mm/vma.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/vma.c b/mm/vma.c index be64f781a3aa..89073980de46 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -2781,6 +2781,8 @@ static unsigned long __mmap_region(struct file *file, unsigned long addr, if (map.charged) vm_unacct_memory(map.charged); abort_munmap: + if (map.file_doesnt_need_get && map.file) + fput(map.file); vms_abort_munmap_vmas(&map.vms, &map.mas_detach); return error; } -- 2.43.0