Messages in this thread Patch in this message | | | From | Dominique Martinet <> | Subject | [PATCH 01/18] coccinelle: change strncpy+truncation to strlcpy | Date | Fri, 13 Jul 2018 03:14:43 +0200 |
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Besides being simpler, using strlcpy instead of strncpy+truncation fixes part of the following class of new gcc warnings:
drivers/gpu/drm/i915/intel_tv.c: In function ‘intel_tv_get_modes’: drivers/gpu/drm/i915/intel_tv.c:1358:3: error: ‘strncpy’ specified bound 32 equals destination size [-Werror=stringop-truncation] strncpy(mode_ptr->name, input->name, DRM_DISPLAY_MODE_LEN); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors
Note that this is not a proper fix for this warning (and not all of the occurences give the warning either - the strings are not always static). The warning was intended to have developers check the return code of strncpy and act in case of truncation (print a warning, abort the function or something similar if the original string was not nul terminated); the change to strlcpy only works because gcc does not handle the function the same way.
Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Dominique Martinet <asmadeus@codewreck.org> ---
Running this fixes 30 occurences of the problem in 17 different components of the kernel, and while the produced patches are fairly straight-forward I'm not sure who I should expect to pick this up as it is sent as a series. I expect each maintainer will pick their share of the patchs if they agree with it and the rest will just be dropped?
.../coccinelle/misc/strncpy_truncation.cocci | 41 +++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 scripts/coccinelle/misc/strncpy_truncation.cocci
diff --git a/scripts/coccinelle/misc/strncpy_truncation.cocci b/scripts/coccinelle/misc/strncpy_truncation.cocci new file mode 100644 index 000000000000..28b5c2a290ac --- /dev/null +++ b/scripts/coccinelle/misc/strncpy_truncation.cocci @@ -0,0 +1,41 @@ +/// Use strlcpy rather than strncpy(dest,..,sz) + dest[sz-1] = '\0' +/// +// Confidence: High +// Comments: +// Options: --no-includes --include-headers + +virtual patch +virtual context +virtual report +virtual org + +@r@ +expression dest, src, sz; +position p; +@@ + +strncpy@p(dest, src, sz); +dest[sz - 1] = '\0'; + +@script:python depends on org@ +p << r.p; +@@ + +cocci.print_main("strncpy followed by truncation can be strlcpy",p) + +@script:python depends on report@ +p << r.p; +@@ + +msg = "SUGGESTION: strncpy followed by truncation can be strlcpy" +coccilib.report.print_report(p[0],msg) + +@ok depends on patch@ +expression r.dest, r.src, r.sz; +position r.p; +@@ + +-strncpy@p( ++strlcpy( + dest, src, sz); +-dest[sz - 1] = '\0'; -- 2.17.1
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