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Message-ID: <alpine.DEB.2.22.394.2010152246260.2869@hadrien>
Date: Thu, 15 Oct 2020 22:48:44 +0200 (CEST)
From: Julia Lawall <julia.lawall@...ia.fr>
To: Denis Efremov <efremov@...ux.com>
cc: cocci@...teme.lip6.fr, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7] coccinelle: api: add kfree_mismatch script
[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@...ux.com>
> ---
> 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
> +
> +@...oc@
> +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
> + ...
> + }
> +)
> +
> +@...e@
> +expression E;
> +position fok;
> +@@
> +
> + E = \(kvmalloc\|kvzalloc\|kvcalloc\|kvzalloc_node\|kvmalloc_node\|
> + kvmalloc_array\)(...)
> + ...
> + kvfree(E)@fok
> +
> +@...ee 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
> +
> +@...ends 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)
> +
> +@...ee 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
> +
> +@...ends 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)
> +
> +@...ree 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
> +
> +@...ends 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)
> +
> +@...ree_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
> +
> +@...ends 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
> +
> +@...ipt: 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)
> +
> +@...ipt: 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)
> +
> +@...ipt: 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)
> +
> +@...ipt: 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)
> +
> +@...ipt: 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)
> +
> +@...ipt: 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)
> +
> +@...ipt: 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)
> +
> +@...ipt: 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
>
>
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