From 6b77f188969d72254f6bda291f4f2d9fd42f5ecc Mon Sep 17 00:00:00 2001 From: Mian Yousaf Kaukab Date: Tue, 8 Nov 2016 17:45:50 +0100 Subject: [PATCH 2/2] depmod: ignore related modules in depmod_report_cycles MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Only print actual cyclic dependencies. Print count of all the modules in cyclic dependency at the end of the function so that dependent modules which are not in cyclic chain can be ignored. Printing dependent modules which are not in cyclic chain causes buffer overflow as m->modnamesz is not included in buffer size calculations (loop == m is never true). This buffer overflow causes kmod to crash. Update depmod test to reflect the change as well. Reported-by: Andreas Färber Signed-off-by: Mian Yousaf Kaukab --- .../rootfs-pristine/test-depmod/detect-loop/correct.txt | 2 +- tools/depmod.c | 13 ++++++++++++- 2 files changed, 13 insertions(+), 2 deletions(-) Index: kmod-23/testsuite/rootfs-pristine/test-depmod/detect-loop/correct.txt =================================================================== --- kmod-23.orig/testsuite/rootfs-pristine/test-depmod/detect-loop/correct.txt +++ kmod-23/testsuite/rootfs-pristine/test-depmod/detect-loop/correct.txt @@ -1,3 +1,3 @@ -depmod: ERROR: Found 5 modules in dependency cycles! depmod: ERROR: Cycle detected: mod_loop_d -> mod_loop_e -> mod_loop_d depmod: ERROR: Cycle detected: mod_loop_b -> mod_loop_c -> mod_loop_a -> mod_loop_b +depmod: ERROR: Found 5 modules in dependency cycles! Index: kmod-23/tools/depmod.c =================================================================== --- kmod-23.orig/tools/depmod.c +++ kmod-23/tools/depmod.c @@ -1455,7 +1455,7 @@ static void depmod_report_cycles(struct { const char sep[] = " -> "; int ir = 0; - ERR("Found %u modules in dependency cycles!\n", n_roots); + int num_cyclic = 0; while (n_roots > 0) { int is, ie; @@ -1490,6 +1490,7 @@ static void depmod_report_cycles(struct if (m->visited) { int i, n = 0, sz = 0; char *buf; + bool is_cyclic = false; for (i = ie - 1; i >= 0; i--) { struct mod *loop = depmod->modules.array[edges[i]]; @@ -1497,9 +1498,17 @@ static void depmod_report_cycles(struct n++; if (loop == m) { sz += loop->modnamesz - 1; + is_cyclic = true; break; } } + /* Current module not found in dependency list. + * Must be a related module. Ignore it. + */ + if (!is_cyclic) + continue; + + num_cyclic += n; buf = malloc(sz + n * strlen(sep) + 1); sz = 0; @@ -1537,6 +1546,8 @@ static void depmod_report_cycles(struct } } } + + ERR("Found %d modules in dependency cycles!\n", num_cyclic); } static int depmod_calculate_dependencies(struct depmod *depmod)