From a2ceb95e2a7d5bf0270f0d342d2edb560f5cfcf4 Mon Sep 17 00:00:00 2001 From: Jim Warner Date: Thu, 17 Aug 2017 01:11:11 -0500 Subject: [PATCH] top: protect against the anomalous 'Mem' graph display Until this patch, top falsely assumed that there would always be some (small) amount of physical memory after subtracting 'used' and 'available' from the total. But as the issue referenced below attests, a sum of 'used' and 'available' might exceed that total memory amount. I'm not sure if this is a problem with our calculation of the 'used' amount, a flaw in the kernel 'available' algorithms or some other reason I cannot even imagine. Anyway, this patch protects against such a contingency through the following single line addition of new code . if (pct_used + pct_misc > 100.0 || pct_misc < 0) ... The check for less than zero is not actually necessary as long as the source numbers remain unsigned. However should they ever become signed, we'll have protection. [ Most of the changes in this commit simply separate ] [ a variable's definition from its associated logic. ] Reference(s): https://gitlab.com/procps-ng/procps/issues/64 Signed-off-by: Jim Warner --- top/top.c | 19 ++++++++++++------- 1 files changed, 12 insertions(+), 7 deletions(-) diff --git a/top/top.c b/top/top.c index 385df1d..948805e 100644 --- a/top/top.c +++ b/top/top.c @@ -5249,21 +5249,26 @@ numa_nope: { "%-.*s~4", "%-.*s~6", "%-.*s~6", Graph_blks } }; char used[SMLBUFSIZ], util[SMLBUFSIZ], dual[MEDBUFSIZ]; - int ix = w->rc.graph_mems - 1; - float pct_used = (float)kb_main_used * (100.0 / (float)kb_main_total), + float pct_used, pct_misc, pct_swap; + int ix, num_used, num_misc; + + pct_used = (float)kb_main_used * (100.0 / (float)kb_main_total); #ifdef MEMGRAPH_OLD - pct_misc = (float)(kb_main_buffers + kb_main_cached) * (100.0 / (float)kb_main_total), + pct_misc = (float)(kb_main_buffers + kb_main_cached) * (100.0 / (float)kb_main_total); #else - pct_misc = (float)(kb_main_total - kb_main_available - kb_main_used) * (100.0 / (float)kb_main_total), + pct_misc = (float)(kb_main_total - kb_main_available - kb_main_used) * (100.0 / (float)kb_main_total); #endif - pct_swap = kb_swap_total ? (float)kb_swap_used * (100.0 / (float)kb_swap_total) : 0; + if (pct_used + pct_misc > 100.0 || pct_misc < 0) pct_misc = 0; + pct_swap = kb_swap_total ? (float)kb_swap_used * (100.0 / (float)kb_swap_total) : 0; + ix = w->rc.graph_mems - 1; #ifndef QUICK_GRAPHS - int num_used = (int)((pct_used * Graph_adj) + .5), - num_misc = (int)((pct_misc * Graph_adj) + .5); + num_used = (int)((pct_used * Graph_adj) + .5), + num_misc = (int)((pct_misc * Graph_adj) + .5); if (num_used + num_misc > Graph_len) --num_misc; snprintf(used, sizeof(used), gtab[ix].used, num_used, gtab[ix].type); snprintf(util, sizeof(util), gtab[ix].misc, num_misc, gtab[ix].type); #else + (void)num_used; (void)num_misc; snprintf(used, sizeof(used), gtab[ix].used, (int)((pct_used * Graph_adj) + .5), gtab[ix].type); snprintf(util, sizeof(util), gtab[ix].misc, (int)((pct_misc * Graph_adj) + .4), gtab[ix].type); #endif -- libgit2 0.26.0