On Fri, Apr 16, 2021 at 09:00:12AM +0200, Christophe Leroy wrote: > > > Le 16/04/2021 à 08:44, Daniel Axtens a écrit : > > Hi Lakshmi, > > > > > On 4/15/21 12:14 PM, Lakshmi Ramasubramanian wrote: > > > > > > Sorry - missed copying device-tree and powerpc mailing lists. > > > > > > > There are a few "goto out;" statements before the local variable "fdt" > > > > is initialized through the call to of_kexec_alloc_and_setup_fdt() in > > > > elf64_load(). This will result in an uninitialized "fdt" being passed > > > > to kvfree() in this function if there is an error before the call to > > > > of_kexec_alloc_and_setup_fdt(). > > > > > > > > Initialize the local variable "fdt" to NULL. > > > > > > I'm a huge fan of initialising local variables! But I'm struggling to > > find the code path that will lead to an uninit fdt being returned... > > > > The out label reads in part: > > > > /* Make kimage_file_post_load_cleanup free the fdt buffer for us. */ > > return ret ? ERR_PTR(ret) : fdt; > > > > As far as I can tell, any time we get a non-zero ret, we're going to > > return an error pointer rather than the uninitialised value... > > I don't think GCC is smart enough to detect that. > We disabled uninitialized variable checking for GCC. But actually is something that has been on my mind recently. Smatch is supposed to parse this correctly but there is a bug that affects powerpc and I don't know how to debug it. The kbuild bot is doing cross platform compiles but I don't have one set up on myself. Could someone with Smatch installed test something for me? Or if you don't have Smatch installed then you should definitely install it. :P https://www.spinics.net/lists/smatch/msg00568.html Apply the patch from below and edit the path to point to the correct directory. Then run kchecker and email me the output? ~/path/to/smatch_scripts/kchecker arch/powerpc/kernel/hw_breakpoint.c regads, dan carpenter diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c index 8fc7a14e4d71..f2dfba54e14d 100644 --- a/arch/powerpc/kernel/hw_breakpoint.c +++ b/arch/powerpc/kernel/hw_breakpoint.c @@ -167,13 +167,19 @@ static bool can_co_exist(struct breakpoint *b, struct perf_event *bp) return !(alternate_infra_bp(b, bp) && bp_addr_range_overlap(b->bp, bp)); } +#include "/home/XXX/path/to/smatch/check_debug.h" static int task_bps_add(struct perf_event *bp) { struct breakpoint *tmp; tmp = alloc_breakpoint(bp); - if (IS_ERR(tmp)) + __smatch_about(tmp); + __smatch_debug_on(); + if (IS_ERR(tmp)) { + __smatch_debug_off(); + __smatch_about(tmp); return PTR_ERR(tmp); + } list_add(&tmp->list, &task_bps); return 0;
