From: Sergey Senozhatsky Date: Wed, 11 Mar 2026 08:42:49 +0000 (+0900) Subject: zram: unify and harden algo/priority params handling X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=301f3922009658ee353b3177bc186a12d36b8dd3;p=thirdparty%2Fkernel%2Flinux.git zram: unify and harden algo/priority params handling We have two functions that accept algo= and priority= params - algorithm_params_store() and recompress_store(). This patch unifies and hardens handling of those parameters. There are 4 possible cases: - only priority= provided [recommended] We need to verify that provided priority value is within permitted range for each particular function. - both algo= and priority= provided We cannot prioritize one over another. All we should do is to verify that zram is configured in the way that user-space expects it to be. Namely that zram indeed has compressor algo= setup at given priority=. - only algo= provided [not recommended] We should lookup priority in compressors list. - none provided [not recommended] Just use function's defaults. Link: https://lkml.kernel.org/r/20260311084312.1766036-7-senozhatsky@chromium.org Signed-off-by: Sergey Senozhatsky Suggested-by: Minchan Kim Cc: Brian Geffon Cc: gao xu Cc: Jens Axboe Signed-off-by: Andrew Morton --- diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 48fb6e52de42f..bab21b44bdcb9 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1619,6 +1619,37 @@ static void zram_debugfs_register(struct zram *zram) {}; static void zram_debugfs_unregister(struct zram *zram) {}; #endif +/* Only algo parameter given, lookup by algo name */ +static int lookup_algo_priority(struct zram *zram, const char *algo, + u32 min_prio) +{ + s32 prio; + + for (prio = min_prio; prio < ZRAM_MAX_COMPS; prio++) { + if (!zram->comp_algs[prio]) + continue; + + if (!strcmp(zram->comp_algs[prio], algo)) + return prio; + } + + return -EINVAL; +} + +/* Both algo and priority parameters given, validate them */ +static int validate_algo_priority(struct zram *zram, const char *algo, u32 prio) +{ + if (prio >= ZRAM_MAX_COMPS) + return -EINVAL; + /* No algo at given priority */ + if (!zram->comp_algs[prio]) + return -EINVAL; + /* A different algo at given priority */ + if (strcmp(zram->comp_algs[prio], algo)) + return -EINVAL; + return 0; +} + static void comp_algorithm_set(struct zram *zram, u32 prio, const char *alg) { zram->comp_algs[prio] = alg; @@ -1691,6 +1722,7 @@ static ssize_t algorithm_params_store(struct device *dev, char *args, *param, *val, *algo = NULL, *dict_path = NULL; struct deflate_params deflate_params; struct zram *zram = dev_to_zram(dev); + bool prio_param = false; int ret; deflate_params.winbits = ZCOMP_PARAM_NOT_SET; @@ -1703,6 +1735,7 @@ static ssize_t algorithm_params_store(struct device *dev, return -EINVAL; if (!strcmp(param, "priority")) { + prio_param = true; ret = kstrtoint(val, 10, &prio); if (ret) return ret; @@ -1738,24 +1771,22 @@ static ssize_t algorithm_params_store(struct device *dev, if (init_done(zram)) return -EBUSY; - /* Lookup priority by algorithm name */ - if (algo) { - s32 p; - - prio = -EINVAL; - for (p = ZRAM_PRIMARY_COMP; p < ZRAM_MAX_COMPS; p++) { - if (!zram->comp_algs[p]) - continue; + if (prio_param) { + if (prio < ZRAM_PRIMARY_COMP || prio >= ZRAM_MAX_COMPS) + return -EINVAL; + } - if (!strcmp(zram->comp_algs[p], algo)) { - prio = p; - break; - } - } + if (algo && prio_param) { + ret = validate_algo_priority(zram, algo, prio); + if (ret) + return ret; } - if (prio < ZRAM_PRIMARY_COMP || prio >= ZRAM_MAX_COMPS) - return -EINVAL; + if (algo && !prio_param) { + prio = lookup_algo_priority(zram, algo, ZRAM_PRIMARY_COMP); + if (prio < 0) + return -EINVAL; + } ret = comp_params_store(zram, prio, level, dict_path, &deflate_params); return ret ? ret : len; @@ -2396,9 +2427,6 @@ static int recompress_slot(struct zram *zram, u32 index, struct page *page, void *src; int ret = 0; - if (!zram->comps[prio]) - return -EINVAL; - handle_old = get_slot_handle(zram, index); if (!handle_old) return -EINVAL; @@ -2500,10 +2528,11 @@ static ssize_t recompress_store(struct device *dev, char *args, *param, *val, *algo = NULL; u64 num_recomp_pages = ULLONG_MAX; struct zram_pp_ctl *ctl = NULL; - u32 prio = ZRAM_SECONDARY_COMP; - struct zram_pp_slot *pps; + s32 prio = ZRAM_SECONDARY_COMP; u32 mode = 0, threshold = 0; + struct zram_pp_slot *pps; struct page *page = NULL; + bool prio_param = false; ssize_t ret; args = skip_spaces(buf); @@ -2551,7 +2580,8 @@ static ssize_t recompress_store(struct device *dev, } if (!strcmp(param, "priority")) { - ret = kstrtouint(val, 10, &prio); + prio_param = true; + ret = kstrtoint(val, 10, &prio); if (ret) return ret; continue; @@ -2565,30 +2595,26 @@ static ssize_t recompress_store(struct device *dev, if (!init_done(zram)) return -EINVAL; - if (algo) { - bool found = false; - - for (; prio < ZRAM_MAX_COMPS; prio++) { - if (!zram->comp_algs[prio]) - continue; - - if (!strcmp(zram->comp_algs[prio], algo)) { - found = true; - break; - } - } + if (prio_param) { + if (prio < ZRAM_SECONDARY_COMP || prio >= ZRAM_MAX_COMPS) + return -EINVAL; + } - if (!found) { - ret = -EINVAL; - goto out; - } + if (algo && prio_param) { + ret = validate_algo_priority(zram, algo, prio); + if (ret) + return ret; } - if (prio < ZRAM_SECONDARY_COMP || prio >= ZRAM_MAX_COMPS) { - ret = -EINVAL; - goto out; + if (algo && !prio_param) { + prio = lookup_algo_priority(zram, algo, ZRAM_SECONDARY_COMP); + if (prio < 0) + return -EINVAL; } + if (!zram->comps[prio]) + return -EINVAL; + page = alloc_page(GFP_KERNEL); if (!page) { ret = -ENOMEM;