| Message ID | 20220627164052.2416485-2-atomlin@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] module: Modify module_flags() to accept show_state argument | expand |
Le 27/06/2022 à 18:40, Aaron Tomlin a écrit : > For diagnostic purposes, this patch, in addition to keeping a record/or > track of the last known unloaded module, we now will include the > module's taint flag(s) too e.g: " [last unloaded: fpga_mgr_mod(OE)]" > > Signed-off-by: Aaron Tomlin <atomlin@redhat.com> > --- > kernel/module/main.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/kernel/module/main.c b/kernel/module/main.c > index dcb83cf18d84..0ca6fd38b903 100644 > --- a/kernel/module/main.c > +++ b/kernel/module/main.c > @@ -524,7 +524,12 @@ static struct module_attribute modinfo_##field = { \ > MODINFO_ATTR(version); > MODINFO_ATTR(srcversion); > > -static char last_unloaded_module[MODULE_NAME_LEN+1]; > +/* > + * Maximum number of characters written by module_flags() > + * without a module's state information. > + */ > +#define LAST_UNLOADED_MODULE_NAME_LEN (MODULE_NAME_LEN + MODULE_FLAGS_BUF_SIZE - 2 + 1) > +static char last_unloaded_module[LAST_UNLOADED_MODULE_NAME_LEN]; > > #ifdef CONFIG_MODULE_UNLOAD > > @@ -694,6 +699,7 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user, > { > struct module *mod; > char name[MODULE_NAME_LEN]; > + char buf[LAST_UNLOADED_MODULE_NAME_LEN]; > int ret, forced = 0; > > if (!capable(CAP_SYS_MODULE) || modules_disabled) > @@ -753,8 +759,8 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user, > > async_synchronize_full(); > > - /* Store the name of the last unloaded module for diagnostic purposes */ > strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module)); > + strcat(last_unloaded_module, module_flags(mod, buf, false)); You replace a bounded string copy by an unbounded strict contat. Should you use strlcat() instead ? > > free_module(mod); > /* someone could wait for the module in add_unformed_module() */
On Tue 2022-06-28 05:54 +0000, Christophe Leroy wrote: > > - /* Store the name of the last unloaded module for diagnostic purposes */ > > strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module)); > > + strcat(last_unloaded_module, module_flags(mod, buf, false)); > > You replace a bounded string copy by an unbounded strict contat. > > Should you use strlcat() instead ? Hi Christophe, Why? If I understand correctly, both the destination and source string are NULL-terminated (see module_flags()). So, strcat() should be sufficient. Kind regards,
Le 28/06/2022 à 09:47, Aaron Tomlin a écrit : > On Tue 2022-06-28 05:54 +0000, Christophe Leroy wrote: >>> - /* Store the name of the last unloaded module for diagnostic purposes */ >>> strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module)); >>> + strcat(last_unloaded_module, module_flags(mod, buf, false)); >> >> You replace a bounded string copy by an unbounded strict contat. >> >> Should you use strlcat() instead ? > > Hi Christophe, > > Why? If I understand correctly, both the destination and source string are > NULL-terminated (see module_flags()). So, strcat() should be sufficient. > Are you sure you will never ever end up with a string longer than the length of last_unloaded_module ?
On Tue 2022-06-28 08:16 +0000, Christophe Leroy wrote: > Are you sure you will never ever end up with a string longer than the > length of last_unloaded_module ? If I am not mistaken, the length of 'last_unloaded_module' has been increased to accommodate for: the maximum module name, total module flag count, '(', ')' and '\0'. Kind regards,
On Tue 2022-06-28 08:47 +0100, Aaron Tomlin wrote: > On Tue 2022-06-28 05:54 +0000, Christophe Leroy wrote: > > > - /* Store the name of the last unloaded module for diagnostic purposes */ > > > strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module)); > > > + strcat(last_unloaded_module, module_flags(mod, buf, false)); > > > > You replace a bounded string copy by an unbounded strict contat. > > > > Should you use strlcat() instead ? > > Hi Christophe, > > Why? If I understand correctly, both the destination and source string are > NULL-terminated (see module_flags()). So, strcat() should be sufficient. Hi Luis, Any thoughts on this? As far as I can tell, the destination string cannot be overwritten; albeit, I can use the safer option if you prefer. Kind regards,
On Sun, Jul 03, 2022 at 03:22:18PM +0100, Aaron Tomlin wrote: > On Tue 2022-06-28 08:47 +0100, Aaron Tomlin wrote: > > On Tue 2022-06-28 05:54 +0000, Christophe Leroy wrote: > > > > - /* Store the name of the last unloaded module for diagnostic purposes */ > > > > strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module)); > > > > + strcat(last_unloaded_module, module_flags(mod, buf, false)); > > > > > > You replace a bounded string copy by an unbounded strict contat. > > > > > > Should you use strlcat() instead ? > > > > Hi Christophe, > > > > Why? If I understand correctly, both the destination and source string are > > NULL-terminated (see module_flags()). So, strcat() should be sufficient. > > Hi Luis, > > Any thoughts on this? As far as I can tell, the destination string cannot > be overwritten; albeit, I can use the safer option if you prefer. Yeah I don't like this as-is, it makes it not so easy to follow, I'll reply in my review of your patch now. Luis
On Mon, Jun 27, 2022 at 05:40:52PM +0100, Aaron Tomlin wrote: > For diagnostic purposes, this patch, in addition to keeping a record/or > track of the last known unloaded module, we now will include the > module's taint flag(s) too e.g: " [last unloaded: fpga_mgr_mod(OE)]" > > Signed-off-by: Aaron Tomlin <atomlin@redhat.com> > --- > kernel/module/main.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/kernel/module/main.c b/kernel/module/main.c > index dcb83cf18d84..0ca6fd38b903 100644 > --- a/kernel/module/main.c > +++ b/kernel/module/main.c > @@ -524,7 +524,12 @@ static struct module_attribute modinfo_##field = { \ > MODINFO_ATTR(version); > MODINFO_ATTR(srcversion); > > -static char last_unloaded_module[MODULE_NAME_LEN+1]; > +/* > + * Maximum number of characters written by module_flags() > + * without a module's state information. > + */ > +#define LAST_UNLOADED_MODULE_NAME_LEN (MODULE_NAME_LEN + MODULE_FLAGS_BUF_SIZE - 2 + 1) > +static char last_unloaded_module[LAST_UNLOADED_MODULE_NAME_LEN]; First of all this then confuses a reader easily as one would expect last_unloaded_module always just has the module. Second, "module flags" really throws a user off, as one would expect a module flag is some sort of parameter, but in reality these are just taint flags. So I'd much prefer we split the taint flags out to its own buffer and dump the data to it alone. The first patch seems sensible. Luis > #ifdef CONFIG_MODULE_UNLOAD > > @@ -694,6 +699,7 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user, > { > struct module *mod; > char name[MODULE_NAME_LEN]; > + char buf[LAST_UNLOADED_MODULE_NAME_LEN]; > int ret, forced = 0; > > if (!capable(CAP_SYS_MODULE) || modules_disabled) > @@ -753,8 +759,8 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user, > > async_synchronize_full(); > > - /* Store the name of the last unloaded module for diagnostic purposes */ > strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module)); > + strcat(last_unloaded_module, module_flags(mod, buf, false)); > > free_module(mod); > /* someone could wait for the module in add_unformed_module() */ > -- > 2.34.3 >
diff --git a/kernel/module/main.c b/kernel/module/main.c index dcb83cf18d84..0ca6fd38b903 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -524,7 +524,12 @@ static struct module_attribute modinfo_##field = { \ MODINFO_ATTR(version); MODINFO_ATTR(srcversion); -static char last_unloaded_module[MODULE_NAME_LEN+1]; +/* + * Maximum number of characters written by module_flags() + * without a module's state information. + */ +#define LAST_UNLOADED_MODULE_NAME_LEN (MODULE_NAME_LEN + MODULE_FLAGS_BUF_SIZE - 2 + 1) +static char last_unloaded_module[LAST_UNLOADED_MODULE_NAME_LEN]; #ifdef CONFIG_MODULE_UNLOAD @@ -694,6 +699,7 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user, { struct module *mod; char name[MODULE_NAME_LEN]; + char buf[LAST_UNLOADED_MODULE_NAME_LEN]; int ret, forced = 0; if (!capable(CAP_SYS_MODULE) || modules_disabled) @@ -753,8 +759,8 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user, async_synchronize_full(); - /* Store the name of the last unloaded module for diagnostic purposes */ strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module)); + strcat(last_unloaded_module, module_flags(mod, buf, false)); free_module(mod); /* someone could wait for the module in add_unformed_module() */
For diagnostic purposes, this patch, in addition to keeping a record/or track of the last known unloaded module, we now will include the module's taint flag(s) too e.g: " [last unloaded: fpga_mgr_mod(OE)]" Signed-off-by: Aaron Tomlin <atomlin@redhat.com> --- kernel/module/main.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)