From: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Subject: mm/vmpressure.c: fix a signedness bug in vmpressure_register_event() The "mode" and "level" variables are enums and in this context GCC will treat them as unsigned ints so the error handling is never triggered. I also removed the bogus initializer because it isn't required any more and it's sort of confusing. [akpm@xxxxxxxxxxxxxxxxxxxx: reduce implicit and explicit typecasting] [akpm@xxxxxxxxxxxxxxxxxxxx: fix return value, add comment, per Matthew] Link: http://lkml.kernel.org/r/20190925110449.GO3264@mwanda Fixes: 3cadfa2b9497 ("mm/vmpressure.c: convert to use match_string() helper") Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx> Reviewed-by: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Enrico Weigelt <info@xxxxxxxxx> Cc: Kate Stewart <kstewart@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/vmpressure.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) --- a/mm/vmpressure.c~mm-vmpressure-fix-a-signedness-bug-in-vmpressure_register_event +++ a/mm/vmpressure.c @@ -355,6 +355,9 @@ void vmpressure_prio(gfp_t gfp, struct m * "hierarchy" or "local"). * * To be used as memcg event method. + * + * Return: 0 on success, -ENOMEM on memory failure or -EINVAL if @args could + * not be parsed. */ int vmpressure_register_event(struct mem_cgroup *memcg, struct eventfd_ctx *eventfd, const char *args) @@ -362,7 +365,7 @@ int vmpressure_register_event(struct mem struct vmpressure *vmpr = memcg_to_vmpressure(memcg); struct vmpressure_event *ev; enum vmpressure_modes mode = VMPRESSURE_NO_PASSTHROUGH; - enum vmpressure_levels level = -1; + enum vmpressure_levels level; char *spec, *spec_orig; char *token; int ret = 0; @@ -375,20 +378,18 @@ int vmpressure_register_event(struct mem /* Find required level */ token = strsep(&spec, ","); - level = match_string(vmpressure_str_levels, VMPRESSURE_NUM_LEVELS, token); - if (level < 0) { - ret = level; + ret = match_string(vmpressure_str_levels, VMPRESSURE_NUM_LEVELS, token); + if (ret < 0) goto out; - } + level = ret; /* Find optional mode */ token = strsep(&spec, ","); if (token) { - mode = match_string(vmpressure_str_modes, VMPRESSURE_NUM_MODES, token); - if (mode < 0) { - ret = mode; + ret = match_string(vmpressure_str_modes, VMPRESSURE_NUM_MODES, token); + if (ret < 0) goto out; - } + mode = ret; } ev = kzalloc(sizeof(*ev), GFP_KERNEL); @@ -404,6 +405,7 @@ int vmpressure_register_event(struct mem mutex_lock(&vmpr->events_lock); list_add(&ev->node, &vmpr->events); mutex_unlock(&vmpr->events_lock); + ret = 0; out: kfree(spec_orig); return ret; _
