Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider: - [High] dyndbg: init_bits relies on _DPRINTK_FLAGS_DEFAULT evaluated in wrong translation unit - [Medium] dyndbg: TOCTOU race in ddebug_sync_classbits() causes out-of-sync debug state --
commit 3b29729057e8a4b4e0401fd7f3a74205f701c129 Author: Jim Cromie <[email protected]> dyndbg-API: replace DECLARE_DYNDBG_CLASSMAP This commit replaces DECLARE_DYNDBG_CLASSMAP with an explicit client-server model using DYNAMIC_DEBUG_CLASSMAP_DEFINE and DYNAMIC_DEBUG_CLASSMAP_USE. At module load time, it resolves reference records and automatically applies the initial bitmap to the module. Cc: [email protected] > diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c > index 03dc35af4faa1..566c3860d7bfb 100644 > --- a/lib/dynamic_debug.c > +++ b/lib/dynamic_debug.c [ ... ] > +static void ddebug_sync_classbits(const struct kernel_param *kp, const char > *modname) > +{ > + const struct ddebug_class_param *dcp = kp->arg; > + u32 val, new_bits, init_bits; > + > + if (!dcp || !dcp->map) > + return; > + > + init_bits = (_DPRINTK_FLAGS_DEFAULT & _DPRINTK_FLAGS_PRINT) ? > + CLASSMAP_BITMASK(dcp->map->length) : 0; [Severity: High] Does this evaluate _DPRINTK_FLAGS_DEFAULT in the context of the dynamic debug library rather than the target module's translation unit? Since dynamic_debug.c is not compiled with -DDEBUG, init_bits will always be evaluated as 0 here. Could this prevent the system from properly disabling callsites for modules that are loaded and compiled with -DDEBUG? > + > + switch (dcp->map->map_type) { > + case DD_CLASS_TYPE_DISJOINT_BITS: > + val = READ_ONCE(*dcp->bits); > + new_bits = val; > + v2pr_info(" %s: classbits: 0x%x\n", KP_NAME(kp), new_bits); > + ddebug_apply_class_bitmap(dcp, &new_bits, init_bits, modname); > + break; [ ... ] > @@ -1238,12 +1410,17 @@ static int ddebug_add_module(struct _ddebug_info *di) [ ... ] > mutex_lock(&ddebug_lock); > list_add_tail(&dt->link, &ddebug_tables); > mutex_unlock(&ddebug_lock); > > - vpr_info("%3u debug prints in module %s\n", di->descs.len, > di->mod_name); > + if (dt->info.users.len) > + ddebug_apply_class_users(&dt->info); [Severity: Medium] Could this introduce a time-of-check to time-of-use (TOCTOU) race condition between module loading and concurrent sysfs updates? Once ddebug_add_module() adds the module to ddebug_tables and drops the ddebug_lock, it proceeds to call ddebug_apply_class_users() (which then calls ddebug_sync_classbits()). In ddebug_sync_classbits(), the parameter value is read via READ_ONCE(*dcp->bits) without holding the lock. If a concurrent sysfs write updates the parameter and applies it to all modules in ddebug_tables (including this newly added one), could the module load thread subsequently resume and apply the stale value it just read, leaving this module's debug state out-of-sync with the global parameter? -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=23
