Re: [PATCH v7] coccinelle: api: add kfree_mismatch script

[Julia Lawall]

[See below for a comment]

On Mon, 3 Aug 2020, Denis Efremov wrote:

> Check that alloc and free types of functions match each other.
>
> Signed-off-by: Denis Efremov <efremov@xxxxxxxxx>
> ---
> Changes in v2:
>  - Lines are limited to 80 characters where possible
>  - Confidence changed from High to Medium because of
>    fs/btrfs/send.c:1119 false-positive
>  - __vmalloc_area_node() explicitly excluded from analysis
>    instead of !(file in "mm/vmalloc.c") condition
> Changes in v3:
>  - prints style in org && report modes changed for python2
> Changes in v4:
>  - missing msg argument to print_todo fixed
> Changes in v5:
>  - fix position p in kfree rule
>  - move @kok and @v positions in choice rule after the arguments
>  - remove kvmalloc suggestions
> Changes in v6:
>  - more asterisks added in context mode
>  - second @kok added to the choice rule
> Changes in v7:
>  - file renamed to kfree_mismatch.cocci
>  - python function relevant() removed
>  - additional rule for filtering free positions added
>  - btrfs false-positive fixed
>  - confidence level changed to high
>  - kvfree_switch rule added
>  - names for position variables changed to @a (alloc) and @f (free)
>
>  scripts/coccinelle/api/kfree_mismatch.cocci | 229 ++++++++++++++++++++
>  1 file changed, 229 insertions(+)
>  create mode 100644 scripts/coccinelle/api/kfree_mismatch.cocci
>
> diff --git a/scripts/coccinelle/api/kfree_mismatch.cocci b/scripts/coccinelle/api/kfree_mismatch.cocci
> new file mode 100644
> index 000000000000..9e9ef9fd7a25
> --- /dev/null
> +++ b/scripts/coccinelle/api/kfree_mismatch.cocci
> @@ -0,0 +1,229 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +///
> +/// Check that kvmalloc'ed memory is freed by kfree functions,
> +/// vmalloc'ed by vfree functions and kvmalloc'ed by kvfree
> +/// functions.
> +///
> +// Confidence: High
> +// Copyright: (C) 2020 Denis Efremov ISPRAS
> +// Options: --no-includes --include-headers
> +//
> +
> +virtual patch
> +virtual report
> +virtual org
> +virtual context
> +
> +@alloc@
> +expression E, E1;
> +position kok, vok;
> +@@
> +
> +(
> +  if (...) {
> +    ...
> +    E = \(kmalloc\|kzalloc\|krealloc\|kcalloc\|
> +          kmalloc_node\|kzalloc_node\|kmalloc_array\|
> +          kmalloc_array_node\|kcalloc_node\)(...)@kok
> +    ...
> +  } else {
> +    ...
> +    E = \(vmalloc\|vzalloc\|vmalloc_user\|vmalloc_node\|
> +          vzalloc_node\|vmalloc_exec\|vmalloc_32\|
> +          vmalloc_32_user\|__vmalloc\|__vmalloc_node_range\|
> +          __vmalloc_node\)(...)@vok
> +    ...
> +  }
> +|
> +  E = \(kmalloc\|kzalloc\|krealloc\|kcalloc\|kmalloc_node\|kzalloc_node\|
> +        kmalloc_array\|kmalloc_array_node\|kcalloc_node\)(...)@kok
> +  ... when != E = E1
> +      when any
> +  if (E == NULL) {
> +    ...
> +    E = \(vmalloc\|vzalloc\|vmalloc_user\|vmalloc_node\|
> +          vzalloc_node\|vmalloc_exec\|vmalloc_32\|
> +          vmalloc_32_user\|__vmalloc\|__vmalloc_node_range\|
> +          __vmalloc_node\)(...)@vok
> +    ...
> +  }
> +)
> +
> +@free@
> +expression E;
> +position fok;
> +@@
> +
> +  E = \(kvmalloc\|kvzalloc\|kvcalloc\|kvzalloc_node\|kvmalloc_node\|
> +        kvmalloc_array\)(...)
> +  ...
> +  kvfree(E)@fok
> +
> +@vfree depends on !patch@
> +expression E;
> +position a != alloc.kok;
> +position f != free.fok;
> +@@
> +
> +* E = \(kmalloc\|kzalloc\|krealloc\|kcalloc\|kmalloc_node\|
> +*       kzalloc_node\|kmalloc_array\|kmalloc_array_node\|
> +*       kcalloc_node\)(...)@a
> +  ... when != if (...) { ... E = \(vmalloc\|vzalloc\|vmalloc_user\|vmalloc_node\|vzalloc_node\|vmalloc_exec\|vmalloc_32\|vmalloc_32_user\|__vmalloc\|__vmalloc_node_range\|__vmalloc_node\)(...); ... }
> +      when != is_vmalloc_addr(E)
> +      when any
> +* \(vfree\|vfree_atomic\|kvfree\)(E)@f
> +
> +@depends on patch exists@
> +expression E;
> +position a != alloc.kok;
> +position f != free.fok;
> +@@
> +
> +  E = \(kmalloc\|kzalloc\|krealloc\|kcalloc\|kmalloc_node\|
> +        kzalloc_node\|kmalloc_array\|kmalloc_array_node\|
> +        kcalloc_node\)(...)@a
> +  ... when != if (...) { ... E = \(vmalloc\|vzalloc\|vmalloc_user\|vmalloc_node\|vzalloc_node\|vmalloc_exec\|vmalloc_32\|vmalloc_32_user\|__vmalloc\|__vmalloc_node_range\|__vmalloc_node\)(...); ... }
> +      when != is_vmalloc_addr(E)
> +      when any
> +- \(vfree\|vfree_atomic\|kvfree\)(E)@f
> ++ kfree(E)
> +
> +@kfree depends on !patch@
> +expression E;
> +position a != alloc.vok;
> +position f != free.fok;
> +@@
> +
> +* E = \(vmalloc\|vzalloc\|vmalloc_user\|vmalloc_node\|vzalloc_node\|
> +*       vmalloc_exec\|vmalloc_32\|vmalloc_32_user\|__vmalloc\|
> +*       __vmalloc_node_range\|__vmalloc_node\)(...)@a
> +  ... when != is_vmalloc_addr(E)
> +      when any
> +* \(kfree\|kzfree\|kvfree\)(E)@f
> +
> +@depends on patch exists@
> +expression E;
> +position a != alloc.vok;
> +position f != free.fok;
> +@@
> +
> +  E = \(vmalloc\|vzalloc\|vmalloc_user\|vmalloc_node\|vzalloc_node\|
> +        vmalloc_exec\|vmalloc_32\|vmalloc_32_user\|__vmalloc\|
> +        __vmalloc_node_range\|__vmalloc_node\)(...)@a
> +  ... when != is_vmalloc_addr(E)
> +      when any
> +- \(kfree\|kvfree\)(E)@f
> ++ vfree(E)
> +
> +@kvfree depends on !patch@
> +expression E;
> +position a, f;
> +@@
> +
> +* E = \(kvmalloc\|kvzalloc\|kvcalloc\|kvzalloc_node\|kvmalloc_node\|
> +*       kvmalloc_array\)(...)@a
> +  ... when != is_vmalloc_addr(E)
> +      when any
> +* \(kfree\|kzfree\|vfree\|vfree_atomic\)(E)@f
> +
> +@depends on patch exists@
> +expression E;
> +@@
> +
> +  E = \(kvmalloc\|kvzalloc\|kvcalloc\|kvzalloc_node\|kvmalloc_node\|
> +        kvmalloc_array\)(...)
> +  ... when != is_vmalloc_addr(E)
> +      when any
> +- \(kfree\|vfree\)(E)
> ++ kvfree(E)
> +
> +@kvfree_switch depends on !patch@
> +expression alloc.E;
> +position f != free.fok;
> +@@
> +
> +  ... when != is_vmalloc_addr(E)
> +      when any
> +* \(kfree\|kzfree\|vfree\|vfree_atomic\)(E)@f
> +
> +@depends on patch exists@
> +expression alloc.E;
> +position f != free.fok;
> +@@
> +
> +  ... when != is_vmalloc_addr(E)
> +      when any
> +(
> +- \(kfree\|vfree\)(E)@f
> ++ kvfree(E)
> +|
> +- kzfree(E)@f
> ++ kvfree_sensitive(E)
> +)


The above two rules refer to free.fok, but it is not clear why, because
free.fok only occurs on a kvfree call.  Is there a mistake, or is it just
an unnecessary copy-pasted constraint?

julia


> +
> +@script: python depends on report@
> +a << vfree.a;
> +f << vfree.f;
> +@@
> +
> +msg = "WARNING: kmalloc is used to allocate this memory at line %s" % (a[0].line)
> +coccilib.report.print_report(f[0], msg)
> +
> +@script: python depends on org@
> +a << vfree.a;
> +f << vfree.f;
> +@@
> +
> +msg = "WARNING: kmalloc is used to allocate this memory at line %s" % (a[0].line)
> +coccilib.org.print_todo(f[0], msg)
> +
> +@script: python depends on report@
> +a << kfree.a;
> +f << kfree.f;
> +@@
> +
> +msg = "WARNING: vmalloc is used to allocate this memory at line %s" % (a[0].line)
> +coccilib.report.print_report(f[0], msg)
> +
> +@script: python depends on org@
> +a << kfree.a;
> +f << kfree.f;
> +@@
> +
> +msg = "WARNING: vmalloc is used to allocate this memory at line %s" % (a[0].line)
> +coccilib.org.print_todo(f[0], msg)
> +
> +@script: python depends on report@
> +a << kvfree.a;
> +f << kvfree.f;
> +@@
> +
> +msg = "WARNING: kvmalloc is used to allocate this memory at line %s" % (a[0].line)
> +coccilib.report.print_report(f[0], msg)
> +
> +@script: python depends on org@
> +a << kvfree.a;
> +f << kvfree.f;
> +@@
> +
> +msg = "WARNING: kvmalloc is used to allocate this memory at line %s" % (a[0].line)
> +coccilib.org.print_todo(f[0], msg)
> +
> +@script: python depends on report@
> +ka << alloc.kok;
> +va << alloc.vok;
> +f << kvfree_switch.f;
> +@@
> +
> +msg = "WARNING: kmalloc (line %s) && vmalloc (line %s) are used to allocate this memory" % (ka[0].line, va[0].line)
> +coccilib.report.print_report(f[0], msg)
> +
> +@script: python depends on org@
> +ka << alloc.kok;
> +va << alloc.vok;
> +f << kvfree_switch.f;
> +@@
> +
> +msg = "WARNING: kmalloc (line %s) && vmalloc (line %s) are used to allocate this memory" % (ka[0].line, va[0].line)
> +coccilib.org.print_todo(f[0], msg)
> +
> --
> 2.26.2
>
>