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checkpatch: add uninitialized pointer with __free attribute check 

Uinitialized pointers with __free attribute can cause undefined behavior
as the memory randomly assigned to the pointer is freed automatically when
the pointer goes out of scope.  add check in checkpatch to detect such
issues.

Link: https://lkml.kernel.org/r/20251203-aheev-checkpatch-uninitialized-free-v7-1-841e3b31d8f3@gmail.com
Signed-off-by: Ally Heev <allyheev@gmail.com>
Suggested-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/all/8a4c0b43-cf63-400d-b33d-d9c447b7e0b9@suswa.mountain/
Link: https://lore.kernel.org/all/58fd478f408a34b578ee8d949c5c4b4da4d4f41d.camel@HansenPartnership.com/
Acked-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Joe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: David Hunter <david.hunter.linux@gmail.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: James Bottomley <james.bottomley@HansenPartnership.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Menon, Nishanth <nm@ti.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Viresh Kumar <vireshk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
master
Ally Heev 2025-12-03 20:58:49 +05:30 committed by Andrew Morton
parent e6b4d264c8
commit 01da5216c5
2 changed files with 29 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
Documentation/dev-tools/checkpatch.rst
View File

@ -1009,6 +1009,29 @@ Functions and Variables
return bar;
**UNINITIALIZED_PTR_WITH_FREE**
Pointers with __free attribute should be declared at the place of use
and initialized (see include/linux/cleanup.h). In this case
declarations at the top of the function rule can be relaxed. Not doing
so may lead to undefined behavior as the memory assigned (garbage,
in case not initialized) to the pointer is freed automatically when
the pointer goes out of scope.
Also see: https://lore.kernel.org/lkml/58fd478f408a34b578ee8d949c5c4b4da4d4f41d.camel@HansenPartnership.com/
Example::
type var __free(free_func);
... // var not used, but, in future someone might add a return here
var = malloc(var_size);
...
should be initialized as::
...
type var __free(free_func) = malloc(var_size);
...
Permissions
-----------

6
scripts/checkpatch.pl
View File

@ -7732,6 +7732,12 @@ sub process {
ERROR("MISSING_SENTINEL", "missing sentinel in ID array\n" . "$here\n$stat\n");
}
}
# check for uninitialized pointers with __free attribute
while ($line =~ /\*\s*($Ident)\s+__free\s*\(\s*$Ident\s*\)\s*[,;]/g) {
ERROR("UNINITIALIZED_PTR_WITH_FREE",
"pointer '$1' with __free attribute should be initialized\n" . $herecurr);
}
}
# If we have no input at all, then there is nothing to report on