| Message ID | 20221103142504.278543-2-ajones@ventanamicro.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | Fix /proc/cpuinfo cpumask warning | expand |
| Context | Check | Description |
|---|---|---|
| conchuod/patch_count | success | Link |
| conchuod/cover_letter | success | Series has a cover letter |
| conchuod/tree_selection | success | Guessed tree name to be for-next |
| conchuod/fixes_present | success | Fixes tag not required for -next series |
| conchuod/verify_signedoff | success | Signed-off-by tag matches author and committer |
| conchuod/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| conchuod/module_param | success | Was 0 now: 0 |
| conchuod/build_rv32_defconfig | fail | Build and OK |
| conchuod/build_warn_rv64 | fail | Errors and warnings before: 1 this patch: 1 |
| conchuod/dtb_warn_rv64 | success | Errors and warnings before: 0 this patch: 0 |
| conchuod/header_inline | success | No static functions without inline keyword in header files |
| conchuod/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 9 lines checked |
| conchuod/source_inline | success | Was 0 now: 0 |
| conchuod/build_rv64_nommu_k210_defconfig | fail | Build failed |
| conchuod/verify_fixes | success | No Fixes tag |
| conchuod/build_rv64_nommu_virt_defconfig | fail | Build failed |
On Thu, Nov 03, 2022 at 03:25:04PM +0100, Andrew Jones wrote: > The valid cpumask range is [0, nr_cpu_ids) and cpumask_next() > currently calls find_next_bit() with its input CPU ID number plus one > for the bit number, giving cpumask_next() the range [-1, nr_cpu_ids - 1). > seq_read_iter() and cpuinfo's start and next seq operations implement a > pattern like > > n = cpumask_next(n - 1, mask); > show(n); > while (1) { > ++n; > n = cpumask_next(n - 1, mask); > if (n >= nr_cpu_ids) > break; > show(n); > } > > which will eventually result in cpumask_next() being called with > nr_cpu_ids - 1. A kernel compiled with commit 78e5a3399421 ("cpumask: > fix checking valid cpu range"), but not its revert, commit > 80493877d7d0 ("Revert "cpumask: fix checking valid cpu range"."), > will generate a warning when DEBUG_PER_CPU_MAPS is enabled each time > /proc/cpuinfo is read. Future-proof cpuinfo by checking its input to > cpumask_next() is valid. > > Signed-off-by: Andrew Jones <ajones@ventanamicro.com> > Cc: Yury Norov <yury.norov@gmail.com> Reviewed-by: Yury Norov <yury.norov@gmail.com> > --- > arch/x86/kernel/cpu/proc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c > index 099b6f0d96bd..de3f93ac6e49 100644 > --- a/arch/x86/kernel/cpu/proc.c > +++ b/arch/x86/kernel/cpu/proc.c > @@ -153,6 +153,9 @@ static int show_cpuinfo(struct seq_file *m, void *v) > > static void *c_start(struct seq_file *m, loff_t *pos) > { > + if (*pos == nr_cpu_ids) > + return NULL; > + > *pos = cpumask_next(*pos - 1, cpu_online_mask); > if ((*pos) < nr_cpu_ids) > return &cpu_data(*pos); > -- > 2.37.3
diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c index 099b6f0d96bd..de3f93ac6e49 100644 --- a/arch/x86/kernel/cpu/proc.c +++ b/arch/x86/kernel/cpu/proc.c @@ -153,6 +153,9 @@ static int show_cpuinfo(struct seq_file *m, void *v) static void *c_start(struct seq_file *m, loff_t *pos) { + if (*pos == nr_cpu_ids) + return NULL; + *pos = cpumask_next(*pos - 1, cpu_online_mask); if ((*pos) < nr_cpu_ids) return &cpu_data(*pos);
The valid cpumask range is [0, nr_cpu_ids) and cpumask_next() currently calls find_next_bit() with its input CPU ID number plus one for the bit number, giving cpumask_next() the range [-1, nr_cpu_ids - 1). seq_read_iter() and cpuinfo's start and next seq operations implement a pattern like n = cpumask_next(n - 1, mask); show(n); while (1) { ++n; n = cpumask_next(n - 1, mask); if (n >= nr_cpu_ids) break; show(n); } which will eventually result in cpumask_next() being called with nr_cpu_ids - 1. A kernel compiled with commit 78e5a3399421 ("cpumask: fix checking valid cpu range"), but not its revert, commit 80493877d7d0 ("Revert "cpumask: fix checking valid cpu range"."), will generate a warning when DEBUG_PER_CPU_MAPS is enabled each time /proc/cpuinfo is read. Future-proof cpuinfo by checking its input to cpumask_next() is valid. Signed-off-by: Andrew Jones <ajones@ventanamicro.com> Cc: Yury Norov <yury.norov@gmail.com> --- arch/x86/kernel/cpu/proc.c | 3 +++ 1 file changed, 3 insertions(+)