From cc674ab3c0188002917c8a2c28e4424131f1fd7e Mon Sep 17 00:00:00 2001 From: Li Zetao Date: Fri, 28 Oct 2022 15:37:17 +0800 Subject: mm/mmap: fix memory leak in mmap_region() There is a memory leak reported by kmemleak: unreferenced object 0xffff88817231ce40 (size 224): comm "mount.cifs", pid 19308, jiffies 4295917571 (age 405.880s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 60 c0 b2 00 81 88 ff ff 98 83 01 42 81 88 ff ff `..........B.... backtrace: [] __alloc_file+0x21/0x250 [] alloc_empty_file+0x41/0xf0 [] alloc_file+0x59/0x710 [] alloc_file_pseudo+0x154/0x210 [] __shmem_file_setup+0xff/0x2a0 [] shmem_zero_setup+0x8d/0x160 [] mmap_region+0x1075/0x19d0 [] do_mmap+0x727/0x1110 [] vm_mmap_pgoff+0x112/0x1e0 [] do_syscall_64+0x35/0x80 [] entry_SYSCALL_64_after_hwframe+0x46/0xb0 The root cause was traced to an error handing path in mmap_region() when arch_validate_flags() or mas_preallocate() fails. In the shared anonymous mapping sence, vma will be setuped and mapped with a new shared anonymous file via shmem_zero_setup(). So in this case, the file resource needs to be released. Fix it by calling fput(vma->vm_file) and unmap_region() when arch_validate_flags() or mas_preallocate() returns an error in the shared anonymous mapping sence. Link: https://lkml.kernel.org/r/20221028073717.1179380-1-lizetao1@huawei.com Fixes: d4af56c5c7c6 ("mm: start tracking VMAs with maple tree") Fixes: c462ac288f2c ("mm: Introduce arch_validate_flags()") Signed-off-by: Li Zetao Reviewed-by: Liam R. Howlett Signed-off-by: Andrew Morton --- mm/mmap.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'mm/mmap.c') diff --git a/mm/mmap.c b/mm/mmap.c index 2def55555e05..c3c5c1d6103d 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2674,6 +2674,8 @@ cannot_expand: error = -EINVAL; if (file) goto close_and_free_vma; + else if (vma->vm_file) + goto unmap_and_free_vma; else goto free_vma; } @@ -2682,6 +2684,8 @@ cannot_expand: error = -ENOMEM; if (file) goto close_and_free_vma; + else if (vma->vm_file) + goto unmap_and_free_vma; else goto free_vma; } @@ -2751,7 +2755,7 @@ unmap_and_free_vma: /* Undo any partial mapping done by a device driver. */ unmap_region(mm, mas.tree, vma, prev, next, vma->vm_start, vma->vm_end); - if (vm_flags & VM_SHARED) + if (file && (vm_flags & VM_SHARED)) mapping_unmap_writable(file->f_mapping); free_vma: vm_area_free(vma); -- cgit v1.2.3