On Wed 2025-05-07 16:34:43, Bhupesh wrote: > As Linus mentioned in [1], currently we have several memcpy() use-cases > which use 'current->comm' to copy the task name over to local copies. > For an example: > > ... > char comm[TASK_COMM_LEN]; > memcpy(comm, current->comm, TASK_COMM_LEN); > ... > > These should be modified so that we can later implement approaches > to handle the task->comm's 16-byte length limitation (TASK_COMM_LEN) > is a more modular way (follow-up patches do the same): > > ... > char comm[TASK_COMM_LEN]; > memcpy(comm, current->comm, TASK_COMM_LEN); > comm[TASK_COMM_LEN - 1] = 0; > ... > > The relevant 'memcpy()' users were identified using the following search > pattern: > $ git grep 'memcpy.*->comm\>' > > [1]. https://lore.kernel.org/all/CAHk-=wjAmmHUg6vho1KjzQi2=psR30+CogFd4aXrThr2gsiS4g@xxxxxxxxxxxxxx/ > > --- a/include/linux/coredump.h > +++ b/include/linux/coredump.h > @@ -53,7 +53,8 @@ extern void do_coredump(const kernel_siginfo_t *siginfo); > do { \ > char comm[TASK_COMM_LEN]; \ > /* This will always be NUL terminated. */ \ > - memcpy(comm, current->comm, sizeof(comm)); \ > + memcpy(comm, current->comm, TASK_COMM_LEN); \ > + comm[TASK_COMM_LEN] = '\0'; \ I would expect that we replace this with a helper function/macro which would do the right thing. Why is get_task_comm() not used here, please? > printk_ratelimited(Level "coredump: %d(%*pE): " Format "\n", \ Also the name seems to be used for printing a debug information. I would expect that we could use the bigger buffer here and print the "full" name. Is this planed, please? > task_tgid_vnr(current), (int)strlen(comm), comm, ##__VA_ARGS__); \ > } while (0) \ > diff --git a/include/trace/events/block.h b/include/trace/events/block.h > index bd0ea07338eb..94a941ac2034 100644 > --- a/include/trace/events/block.h > +++ b/include/trace/events/block.h > @@ -214,6 +214,7 @@ DECLARE_EVENT_CLASS(block_rq, > blk_fill_rwbs(__entry->rwbs, rq->cmd_flags); > __get_str(cmd)[0] = '\0'; > memcpy(__entry->comm, current->comm, TASK_COMM_LEN); > + __entry->comm[TASK_COMM_LEN - 1] = '\0'; Same for all other callers. That said, I am not sure if the larger buffer is save in all situations. > ), Best Regards, Petr
