video/logo: fix use logo after free prevention
PATCH 1/1 video/logo: fix use logo after free prevention
After 92b004d1aa9f367c372511ca0330f58216b25703 the logos disappeared on Freescale i.MX53 and i.MX6 SoC's (detected on linux-3.12.37). This happens because the fb_find_logo function is validly called (initdata still not freed) AFTER newly introduced latecall fb_logo_late_init.
Instead of stetting a logos_freed flag somewhere in lateinit, this patch uses system_state=SYSTEM_BOOTING as indication for valid initdata.
--- drivers/video/logo/logo.c | 21 +++++---------------- 1 file changed, 5 insertions(+), 16 deletions(-)
drivers/video/logo/logo.c +5 -16
@@ -21,21 +21,6 @@ static bool nologo;module_param (nologo, bool,0 );MODULE_PARM_DESC (nologo,"Disables startup logo" ); -/* -* Logos are located in the initdata, and will be freed in kernel_init. -* Use late_init to mark the logos as freed to prevent any further use. -*/ - -static bool logos_freed; - -static int __init fb_logo_late_init (void ) -{ - logos_freed = true; -return 0 ; -} - -late_initcall (fb_logo_late_init); -/* logo's are marked __initdata. Use __init_refok to tell * modpost that it is intended that this function uses data * marked __initdata.
@@ -44,7 +29,11 @@ const struct linux_logo * __init_refok fb_find_logo(int depth) {const struct linux_logo *logo =NULL ; -if (nologo || logos_freed) +/* +* Logos are located in the initdata, and will be freed in kernel_init. +* Use system_state to determine, if initdata is still useable. +*/ +if (nologo || system_state !=SYSTEM_BOOTING )return NULL ;if (depth >=1 ) {
Signature · 1 line
1.7.10.4
Hi,
Quoted 8 lines · Manfred Schlaegl
After
92b004d1aa9f367c372511ca0330f58216b25703the logos disappeared on Freescale i.MX53 and i.MX6 SoC's (detected on linux-3.12.37). This happens because thefb_find_logofunction is validly called (initdata still not freed) AFTER newly introduced latecallfb_logo_late_init.Instead of stetting a
logos_freedflag somewhere in lateinit, this patch uses system_state=SYSTEM_BOOTING as indication for valid initdata.
The kernel init does free_initmem() call before setting the system_state to SYSTEM_RUNNING, so there's a period of time when the logos are freed, but the check in you patch does not catch it.
Tomi