On Wed, Oct 16, 2024 at 05:54:58PM +0800, Zheng Zengkai wrote: > As suggested by Marc and Lorenzo, first we need to check whether the > 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 v4: > - remove the tmp pointer to make the code more concise. > > Changes in v3: > - based on Marc's patch and reuse the for_each_platform_timer() loop > Link to v3: https://lore.kernel.org/linux-arm-kernel/20241015152602.184108-1-zhengzengkai@xxxxxxxxxx/ > > 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/ > > Link to previous related patches: > https://lore.kernel.org/all/20241008082429.33646-1-zhengzengkai@xxxxxxxxxx/ > https://lore.kernel.org/all/20240930030716.179992-1-zhengzengkai@xxxxxxxxxx/ > --- > drivers/acpi/arm64/gtdt.c | 29 ++++++++++++++++++++--------- > 1 file changed, 20 insertions(+), 9 deletions(-) Reviewed-by: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx> > diff --git a/drivers/acpi/arm64/gtdt.c b/drivers/acpi/arm64/gtdt.c > index c0e77c1c8e09..d7c4e1b9915b 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; \ > + for (_g = acpi_gtdt_desc.platform_timer; platform_timer_valid(_g);\ > _g = next_platform_timer(_g)) > > static inline bool is_timer_block(void *platform_timer) > @@ -157,6 +163,7 @@ int __init acpi_gtdt_init(struct acpi_table_header *table, > { > void *platform_timer; > struct acpi_table_gtdt *gtdt; > + int cnt = 0; > > gtdt = container_of(table, struct acpi_table_gtdt, header); > acpi_gtdt_desc.gtdt = gtdt; > @@ -176,12 +183,16 @@ int __init acpi_gtdt_init(struct acpi_table_header *table, > return 0; > } > > - platform_timer = (void *)gtdt + gtdt->platform_timer_offset; > - if (platform_timer < (void *)table + sizeof(struct acpi_table_gtdt)) { > + acpi_gtdt_desc.platform_timer = (void *)gtdt + gtdt->platform_timer_offset; > + for_each_platform_timer(platform_timer) > + cnt++; > + > + if (cnt != gtdt->platform_timer_count) { > + acpi_gtdt_desc.platform_timer = NULL; > pr_err(FW_BUG "invalid timer data.\n"); > return -EINVAL; > } > - acpi_gtdt_desc.platform_timer = platform_timer; > + > if (platform_timer_count) > *platform_timer_count = gtdt->platform_timer_count; > > -- > 2.20.1 >
