On Wed, Nov 11 2020 at 6:45am -0500,
Colin Ian King <colin.king@xxxxxxxxxxxxx> wrote:
> Hi,
>
> Static analysis on linux-next has detected an initialized variable issue
> with the following recent commit:
>
> commit 28784347451fdbf4671ba97018f816041ba2306a
> Author: Mike Snitzer <snitzer@xxxxxxxxxx>
> Date: Tue Nov 10 13:41:53 2020 -0500
>
> dm: rename multipath path selector source files to have "dm-ps" prefix
>
> The analysis is as follows:
>
> 43
> static int ioa_add_path(struct path_selector *ps, struct dm_path *path,
> 44 int argc, char **argv, char **error)
> 45 {
> 46 struct selector *s = ps->context;
> 47 struct path_info *pi = NULL;
> 1. var_decl: Declaring variable cpu without initializer.
>
> 48 unsigned int cpu;
> 49 int ret;
> 50
> 2. Condition argc != 1, taking false branch.
>
> 51 if (argc != 1) {
> 52 *error = "io-affinity ps: invalid number of arguments";
> 53 return -EINVAL;
> 54 }
> 55
>
> Uninitialized scalar variable (UNINIT)
> 3. uninit_use_in_call: Using uninitialized value cpu when calling
> __cpu_to_node.
>
> 56 pi = kzalloc_node(sizeof(*pi), GFP_KERNEL, cpu_to_node(cpu));
> 57 if (!pi) {
> 58 *error = "io-affinity ps: Error allocating path context";
> 59 return -ENOMEM;
> 60 }
Valid report, but it focuses on a follow-on commit that is just noise.
The commit "dm mpath: add IO affinity path selector" is what is in
quesation, see:
https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-5.11&id=c3d0a31e609e299836fa6ced28cb9ec06b408181
Regardless, Mike Christie, Colin's report has identified a bug.
Please advise on how you'd like to fix ioa_add_path()'s allocation of
'struct path_info'.. pretty sure 'cpu' will default to 0 (on stack)
despite no explicit initialization... so code "works" but does not
do so with a specific cpu allocation affinity.
Mike
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