On Tue, Oct 15, 2024 at 11:26:02PM +0800, Zheng Zengkai wrote: > As suggested by Marc and Lorenzo, first we need to check whether the I would just describe the change, the tags and Link: are there to describe this patch history. > platform_timer entry pointer is within gtdt bounds (< gtdt_end) before > de-referencing what it points at to detect the length of the platform > timer struct and then check that the length of current platform_timer > struct is also valid, i.e. the length is not zero and within gtdt_end. > Now next_platform_timer() only checks against gtdt_end for the entry of > subsequent platform timer without checking the length of it and will > not report error if the check failed and the existing check in function > acpi_gtdt_init() is also not enough. > > Modify the for_each_platform_timer() iterator and use it combined with > a dedicated check function platform_timer_valid() to do the check > against table length (gtdt_end) for each element of platform timer > array in function acpi_gtdt_init(), making sure that both their entry > and length actually fit in the table. > > Suggested-by: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx> > Co-developed-by: Marc Zyngier <maz@xxxxxxxxxx> > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> > Signed-off-by: Zheng Zengkai <zhengzengkai@xxxxxxxxxx> > --- > Changes in v3: > - based on Marc's patch and reuse the for_each_platform_timer() loop > > Changes in v2: > - Check against gtdt_end for both entry and len of each array element > Link to v2: https://lore.kernel.org/linux-arm-kernel/20241012085343.6594-1-zhengzengkai@xxxxxxxxxx/ > > Link to v1: https://lore.kernel.org/all/20241010144703.113728-1-zhengzengkai@xxxxxxxxxx/ > --- > drivers/acpi/arm64/gtdt.c | 32 +++++++++++++++++++++----------- > 1 file changed, 21 insertions(+), 11 deletions(-) > > diff --git a/drivers/acpi/arm64/gtdt.c b/drivers/acpi/arm64/gtdt.c > index c0e77c1c8e09..3583c99afb0d 100644 > --- a/drivers/acpi/arm64/gtdt.c > +++ b/drivers/acpi/arm64/gtdt.c > @@ -36,19 +36,25 @@ struct acpi_gtdt_descriptor { > > static struct acpi_gtdt_descriptor acpi_gtdt_desc __initdata; > > -static inline __init void *next_platform_timer(void *platform_timer) > +static __init bool platform_timer_valid(void *platform_timer) > { > struct acpi_gtdt_header *gh = platform_timer; > > - platform_timer += gh->length; > - if (platform_timer < acpi_gtdt_desc.gtdt_end) > - return platform_timer; > + return (platform_timer >= (void *)(acpi_gtdt_desc.gtdt + 1) && > + platform_timer < acpi_gtdt_desc.gtdt_end && > + gh->length != 0 && > + platform_timer + gh->length <= acpi_gtdt_desc.gtdt_end); > +} > + > +static __init void *next_platform_timer(void *platform_timer) > +{ > + struct acpi_gtdt_header *gh = platform_timer; > > - return NULL; > + return platform_timer + gh->length; > } > > -#define for_each_platform_timer(_g) \ > - for (_g = acpi_gtdt_desc.platform_timer; _g; \ > +#define for_each_platform_timer(_g, first_entry) \ > + for (_g = first_entry; platform_timer_valid(_g); \ > _g = next_platform_timer(_g)) > > static inline bool is_timer_block(void *platform_timer) > @@ -155,8 +161,9 @@ bool __init acpi_gtdt_c3stop(int type) > int __init acpi_gtdt_init(struct acpi_table_header *table, > int *platform_timer_count) > { > - void *platform_timer; > + void *platform_timer, *tmp; It makes more sense - thank you and Marc. Nit: you don't really need another pointer (ie tmp) but you may keep it if that makes the code clearer - all you need to do is using platform_timer as an iterator and initialize acpi_gtdt_desc.platform_timer = (void *)gtdt + gtdt->platform_timer_offset; if all checks passed (you are using tmp just because after the loop platform_timer can't be used to initialize acpi_gtdt_desc.platform_timer). Reviewed-by: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx> (now let's see if this survives GTDTs out there :)) > struct acpi_table_gtdt *gtdt; > + int cnt = 0; > > gtdt = container_of(table, struct acpi_table_gtdt, header); > acpi_gtdt_desc.gtdt = gtdt; > @@ -177,7 +184,10 @@ int __init acpi_gtdt_init(struct acpi_table_header *table, > } > > platform_timer = (void *)gtdt + gtdt->platform_timer_offset; > - if (platform_timer < (void *)table + sizeof(struct acpi_table_gtdt)) { > + for_each_platform_timer(tmp, platform_timer) > + cnt++; > + > + if (cnt != gtdt->platform_timer_count) { > pr_err(FW_BUG "invalid timer data.\n"); > return -EINVAL; > } > @@ -305,7 +315,7 @@ int __init acpi_arch_timer_mem_init(struct arch_timer_mem *timer_mem, > void *platform_timer; > > *timer_count = 0; > - for_each_platform_timer(platform_timer) { > + for_each_platform_timer(platform_timer, acpi_gtdt_desc.platform_timer) { > if (is_timer_block(platform_timer)) { > ret = gtdt_parse_timer_block(platform_timer, timer_mem); > if (ret) > @@ -398,7 +408,7 @@ static int __init gtdt_sbsa_gwdt_init(void) > if (ret || !timer_count) > goto out_put_gtdt; > > - for_each_platform_timer(platform_timer) { > + for_each_platform_timer(platform_timer, acpi_gtdt_desc.platform_timer) { > if (is_non_secure_watchdog(platform_timer)) { > ret = gtdt_import_sbsa_gwdt(platform_timer, gwdt_count); > if (ret) > -- > 2.20.1 >
