| Message ID | 20221027025837.136492-1-lizetao1@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/mmap: Fix memory leak in mmap_region() | expand |
* Li Zetao <lizetao1@huawei.com> [221026 21:55]: > 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: > [<ffffffff81936171>] __alloc_file+0x21/0x250 > [<ffffffff81937051>] alloc_empty_file+0x41/0xf0 > [<ffffffff81937159>] alloc_file+0x59/0x710 > [<ffffffff81937964>] alloc_file_pseudo+0x154/0x210 > [<ffffffff81741dbf>] __shmem_file_setup+0xff/0x2a0 > [<ffffffff817502cd>] shmem_zero_setup+0x8d/0x160 > [<ffffffff817cc1d5>] mmap_region+0x1075/0x19d0 > [<ffffffff817cd257>] do_mmap+0x727/0x1110 > [<ffffffff817518b2>] vm_mmap_pgoff+0x112/0x1e0 > [<ffffffff83adf955>] do_syscall_64+0x35/0x80 > [<ffffffff83c0006a>] 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) when arch_validate_flags() or > mas_preallocate() returns an error. And for the beauty of the code, > put fput() under mapping_unmap_writable(). It does look like the unrolling is in the wrong order in that section. > > Fixes: d4af56c5c7c6 ("mm: start tracking VMAs with maple tree") > Fixes: c462ac288f2c ("mm: Introduce arch_validate_flags()") > Signed-off-by: Li Zetao <lizetao1@huawei.com> > --- > mm/mmap.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index e270057ed04e..8530195b3ec5 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -2674,6 +2674,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr, > error = -EINVAL; > if (file) > goto close_and_free_vma; > + else if (vm_flags & VM_SHARED) > + goto put_vma_file; > else > goto free_vma; > } > @@ -2682,6 +2684,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr, > error = -ENOMEM; > if (file) > goto close_and_free_vma; > + else if (vm_flags & VM_SHARED) > + goto put_vma_file; > else > goto free_vma; > } I am not happy about this getting more complex as it already duplicates too much code. > @@ -2746,13 +2750,13 @@ unsigned long mmap_region(struct file *file, unsigned long addr, > if (vma->vm_ops && vma->vm_ops->close) > vma->vm_ops->close(vma); > unmap_and_free_vma: > - fput(vma->vm_file); > - vma->vm_file = NULL; > - > /* 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) Could we change the above if to "if (file && vm_flags & VM_SHARED)" and jump to unmap_and_free_vma "if (vma->vm_file)"? We could then drop your new goto label. I still think the reodering is correct and worth while. Or am I missing something? > mapping_unmap_writable(file->f_mapping); > +put_vma_file: > + fput(vma->vm_file); > + vma->vm_file = NULL; > free_vma: > vm_area_free(vma); > unacct_error: > -- > 2.31.1 >
Hi, On 2022/10/27 15:30, Liam Howlett wrote: > * Li Zetao <lizetao1@huawei.com> [221026 21:55]: >> 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: >> [<ffffffff81936171>] __alloc_file+0x21/0x250 >> [<ffffffff81937051>] alloc_empty_file+0x41/0xf0 >> [<ffffffff81937159>] alloc_file+0x59/0x710 >> [<ffffffff81937964>] alloc_file_pseudo+0x154/0x210 >> [<ffffffff81741dbf>] __shmem_file_setup+0xff/0x2a0 >> [<ffffffff817502cd>] shmem_zero_setup+0x8d/0x160 >> [<ffffffff817cc1d5>] mmap_region+0x1075/0x19d0 >> [<ffffffff817cd257>] do_mmap+0x727/0x1110 >> [<ffffffff817518b2>] vm_mmap_pgoff+0x112/0x1e0 >> [<ffffffff83adf955>] do_syscall_64+0x35/0x80 >> [<ffffffff83c0006a>] 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) when arch_validate_flags() or >> mas_preallocate() returns an error. And for the beauty of the code, >> put fput() under mapping_unmap_writable(). > It does look like the unrolling is in the wrong order in that section. > >> Fixes: d4af56c5c7c6 ("mm: start tracking VMAs with maple tree") >> Fixes: c462ac288f2c ("mm: Introduce arch_validate_flags()") >> Signed-off-by: Li Zetao <lizetao1@huawei.com> >> --- >> mm/mmap.c | 10 +++++++--- >> 1 file changed, 7 insertions(+), 3 deletions(-) >> >> diff --git a/mm/mmap.c b/mm/mmap.c >> index e270057ed04e..8530195b3ec5 100644 >> --- a/mm/mmap.c >> +++ b/mm/mmap.c >> @@ -2674,6 +2674,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr, >> error = -EINVAL; >> if (file) >> goto close_and_free_vma;I will modify it in the second version >> + else if (vm_flags & VM_SHARED) >> + goto put_vma_file; >> else >> goto free_vma; >> } >> @@ -2682,6 +2684,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr, >> error = -ENOMEM; >> if (file) >> goto close_and_free_vma; >> + else if (vm_flags & VM_SHARED) >> + goto put_vma_file; >> else >> goto free_vma; >> } > I am not happy about this getting more complex as it already duplicates > too much code. It's true that my modification would cause the code to further complicate. I will rework it in the next version. >> @@ -2746,13 +2750,13 @@ unsigned long mmap_region(struct file *file, unsigned long addr, >> if (vma->vm_ops && vma->vm_ops->close) >> vma->vm_ops->close(vma); >> unmap_and_free_vma: >> - fput(vma->vm_file); >> - vma->vm_file = NULL; >> - >> /* 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) > Could we change the above if to "if (file && vm_flags & VM_SHARED)" and > jump to unmap_and_free_vma "if (vma->vm_file)"? We could then drop your > new goto label. I still think the reodering is correct and worth while. > > Or am I missing something? Thanks for your constructive comments. >> mapping_unmap_writable(file->f_mapping); >> +put_vma_file: >> + fput(vma->vm_file); >> + vma->vm_file = NULL; >> free_vma: >> vm_area_free(vma); >> unacct_error: >> -- >> 2.31.1 Regards, Li Zetao
diff --git a/mm/mmap.c b/mm/mmap.c index e270057ed04e..8530195b3ec5 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2674,6 +2674,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr, error = -EINVAL; if (file) goto close_and_free_vma; + else if (vm_flags & VM_SHARED) + goto put_vma_file; else goto free_vma; } @@ -2682,6 +2684,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr, error = -ENOMEM; if (file) goto close_and_free_vma; + else if (vm_flags & VM_SHARED) + goto put_vma_file; else goto free_vma; } @@ -2746,13 +2750,13 @@ unsigned long mmap_region(struct file *file, unsigned long addr, if (vma->vm_ops && vma->vm_ops->close) vma->vm_ops->close(vma); unmap_and_free_vma: - fput(vma->vm_file); - vma->vm_file = NULL; - /* 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) mapping_unmap_writable(file->f_mapping); +put_vma_file: + fput(vma->vm_file); + vma->vm_file = NULL; free_vma: vm_area_free(vma); unacct_error:
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: [<ffffffff81936171>] __alloc_file+0x21/0x250 [<ffffffff81937051>] alloc_empty_file+0x41/0xf0 [<ffffffff81937159>] alloc_file+0x59/0x710 [<ffffffff81937964>] alloc_file_pseudo+0x154/0x210 [<ffffffff81741dbf>] __shmem_file_setup+0xff/0x2a0 [<ffffffff817502cd>] shmem_zero_setup+0x8d/0x160 [<ffffffff817cc1d5>] mmap_region+0x1075/0x19d0 [<ffffffff817cd257>] do_mmap+0x727/0x1110 [<ffffffff817518b2>] vm_mmap_pgoff+0x112/0x1e0 [<ffffffff83adf955>] do_syscall_64+0x35/0x80 [<ffffffff83c0006a>] 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) when arch_validate_flags() or mas_preallocate() returns an error. And for the beauty of the code, put fput() under mapping_unmap_writable(). Fixes: d4af56c5c7c6 ("mm: start tracking VMAs with maple tree") Fixes: c462ac288f2c ("mm: Introduce arch_validate_flags()") Signed-off-by: Li Zetao <lizetao1@huawei.com> --- mm/mmap.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)