On Fri, 17 Jul 2020, Denis Efremov wrote:
> Check for memset()/memzero_explicit() followed by kfree()/vfree()/kvfree().
>
> Signed-off-by: Denis Efremov <efre...@linux.com>
Applied.
> ---
> Changes in v2:
> - memset_explicit() added
> - kvfree_sensitive() added
> - forall added to r1
> - ... between memset and kfree added
> Changes in v3:
> - Explicit filter for definitions instead of !(file in "...") conditions
> - type T added to match casts
> - memzero_explicit() patterns fixed
> - additional rule "cond" added to filter false-positives
> Changes in v4:
> - memset call fixed in rp_memset
> - @m added to rp_memset,rp_memzero rules
>
> scripts/coccinelle/api/kzfree.cocci | 101 ++++++++++++++++++++++++++++
> 1 file changed, 101 insertions(+)
> create mode 100644 scripts/coccinelle/api/kzfree.cocci
>
> diff --git a/scripts/coccinelle/api/kzfree.cocci
> b/scripts/coccinelle/api/kzfree.cocci
> new file mode 100644
> index 000000000000..33625bd7cec9
> --- /dev/null
> +++ b/scripts/coccinelle/api/kzfree.cocci
> @@ -0,0 +1,101 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +///
> +/// Use kzfree, kvfree_sensitive rather than memset or
> +/// memzero_explicit followed by kfree
> +///
> +// Confidence: High
> +// Copyright: (C) 2020 Denis Efremov ISPRAS
> +// Options: --no-includes --include-headers
> +//
> +// Keywords: kzfree, kvfree_sensitive
> +//
> +
> +virtual context
> +virtual patch
> +virtual org
> +virtual report
> +
> +@initialize:python@
> +@@
> +# kmalloc_oob_in_memset uses memset to explicitly trigger out-of-bounds
> access
> +filter = frozenset(['kmalloc_oob_in_memset', 'kzfree', 'kvfree_sensitive'])
> +
> +def relevant(p):
> + return not (filter & {el.current_element for el in p})
> +
> +@cond@
> +position ok;
> +@@
> +
> +if (...)
> + \(memset@ok\|memzero_explicit@ok\)(...);
> +
> +@r depends on !patch forall@
> +expression E;
> +position p : script:python() { relevant(p) };
> +position m != cond.ok;
> +type T;
> +@@
> +
> +(
> +* memset@m((T)E, 0, ...);
> +|
> +* memzero_explicit@m((T)E, ...);
> +)
> + ... when != E
> + when strict
> +* \(kfree\|vfree\|kvfree\)(E)@p;
> +
> +@rp_memzero depends on patch@
> +expression E, size;
> +position p : script:python() { relevant(p) };
> +position m != cond.ok;
> +type T;
> +@@
> +
> +- memzero_explicit@m((T)E, size);
> + ... when != E
> + when strict
> +// TODO: uncomment when kfree_sensitive will be merged.
> +// Only this case is commented out because developers
> +// may not like patches like this since kzfree uses memset
> +// internally (not memzero_explicit).
> +//(
> +//- kfree(E)@p;
> +//+ kfree_sensitive(E);
> +//|
> +- \(vfree\|kvfree\)(E)@p;
> ++ kvfree_sensitive(E, size);
> +//)
> +
> +@rp_memset depends on patch@
> +expression E, size;
> +position p : script:python() { relevant(p) };
> +position m != cond.ok;
> +type T;
> +@@
> +
> +- memset@m((T)E, 0, size);
> + ... when != E
> + when strict
> +(
> +- kfree(E)@p;
> ++ kzfree(E);
> +|
> +- \(vfree\|kvfree\)(E)@p;
> ++ kvfree_sensitive(E, size);
> +)
> +
> +@script:python depends on report@
> +p << r.p;
> +@@
> +
> +coccilib.report.print_report(p[0],
> + "WARNING: opportunity for kzfree/kvfree_sensitive")
> +
> +@script:python depends on org@
> +p << r.p;
> +@@
> +
> +coccilib.org.print_todo(p[0],
> + "WARNING: opportunity for kzfree/kvfree_sensitive")
> --
> 2.26.2
>
>
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