Re: [PATCH] kernel: kallsyms: parameters checking, for EXPORT_SYMBOL_GPL functions
On 2013年04月11日 10:52, Rusty Russell wrote: >>> >> Or is someone already doing this? >>> >> >> > >> > really has: >> > >> > kernel: __wake_up_sync_key in kernel/sched/core.c. >> > lib: *printf. >> > mm: kfree. > No, I mean "is someone calling these functions with NULL". > > Cheers, > Rusty. > > often "kfree(NULL)", that is ok. it will let caller easier using it. also often give 0 size to snprintf, it still let caller easy using. if we treat EXPORT functions of kallsyms as commonly used (or we want to) I suggest to give parameter check for them. thanks. :-) -- Chen Gang Asianux Corporation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] kernel: kallsyms: parameters checking, for EXPORT_SYMBOL_GPL functions
Chen Gang writes: > On 2013年04月10日 14:57, Rusty Russell wrote: >> Chen Gang writes: >>> > for EXPORT_SYMBOL_GPL functions, necessary to check their parameters. >>> > >>> > Signed-off-by: Chen Gang >> Why? >> >> If someone misuses these functions, they crash and thus indicate that >> the caller shouldn't do that. >> > > for me, I think: > > if it is used by self (such as static functions): > I prefer to crash immediatly. > it will help us to find issue, quickly. > > if it can be used by others (such as EXPORT_SYMBOL_GPL): > I prefer to return fail and tell caller that parameter is invalid. > it is more polite to callers, and still indicate it may be an issue. > > :-) I disagree. Calling with invalid parameters is a bug. You've just covered up some cases of invalid use and made it less likely to be found. Because the caller won't notice they screwed up. We could sprinkle WARN_ON() everywhere, but I prefer the crash. Even harder to ignore. There's no limit to how many of these checks we could put in, and we can *never* take them out. I don't want to code that way. >> Or is someone already doing this? >> > > really has: > > kernel: __wake_up_sync_key in kernel/sched/core.c. > lib: *printf. > mm: kfree. No, I mean "is someone calling these functions with NULL". Cheers, Rusty. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] kernel: kallsyms: parameters checking, for EXPORT_SYMBOL_GPL functions
On 2013年04月10日 14:57, Rusty Russell wrote: > Chen Gang writes: >> > for EXPORT_SYMBOL_GPL functions, necessary to check their parameters. >> > >> > Signed-off-by: Chen Gang > Why? > > If someone misuses these functions, they crash and thus indicate that > the caller shouldn't do that. > for me, I think: if it is used by self (such as static functions): I prefer to crash immediatly. it will help us to find issue, quickly. if it can be used by others (such as EXPORT_SYMBOL_GPL): I prefer to return fail and tell caller that parameter is invalid. it is more polite to callers, and still indicate it may be an issue. :-) > Or is someone already doing this? > really has: kernel: __wake_up_sync_key in kernel/sched/core.c. lib: *printf. mm: kfree. > Confused, > Rusty. > -- Chen Gang Asianux Corporation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] kernel: kallsyms: parameters checking, for EXPORT_SYMBOL_GPL functions
Chen Gang writes:
> for EXPORT_SYMBOL_GPL functions, necessary to check their parameters.
>
> Signed-off-by: Chen Gang
Why?
If someone misuses these functions, they crash and thus indicate that
the caller shouldn't do that.
Or is someone already doing this?
Confused,
Rusty.
> ---
> kernel/kallsyms.c | 12
> 1 files changed, 12 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
> index 2169fee..4ba57a9 100644
> --- a/kernel/kallsyms.c
> +++ b/kernel/kallsyms.c
> @@ -175,6 +175,9 @@ unsigned long kallsyms_lookup_name(const char *name)
> unsigned long i;
> unsigned int off;
>
> + if (!name || !name[0])
> + return 0;
> +
> for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
> off = kallsyms_expand_symbol(off, namebuf);
>
> @@ -194,6 +197,9 @@ int kallsyms_on_each_symbol(int (*fn)(void *, const char
> *, struct module *,
> unsigned int off;
> int ret;
>
> + if (!fn)
> + return -EINVAL;
> +
> for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
> off = kallsyms_expand_symbol(off, namebuf);
> ret = fn(data, namebuf, NULL, kallsyms_addresses[i]);
> @@ -382,6 +388,9 @@ static int __sprint_symbol(char *buffer, unsigned long
> address,
> */
> int sprint_symbol(char *buffer, unsigned long address)
> {
> + if (!buffer)
> + return 0;
> +
> return __sprint_symbol(buffer, address, 0, 1);
> }
> EXPORT_SYMBOL_GPL(sprint_symbol);
> @@ -399,6 +408,9 @@ EXPORT_SYMBOL_GPL(sprint_symbol);
> */
> int sprint_symbol_no_offset(char *buffer, unsigned long address)
> {
> + if (!buffer)
> + return 0;
> +
> return __sprint_symbol(buffer, address, 0, 0);
> }
> EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
> --
> 1.7.7.6
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