Patch "s390/decompressor: fix initrd corruption caused by bss clear" has been added to the 4.10-stable tree
Subsystems (2)
This is a note to let you know that I've just added the patch titled
s390/decompressor: fix initrd corruption caused by bss clear
to the 4.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-decompressor-fix-initrd-corruption-caused-by-bss-clear.patch
and it can be found in the queue-4.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.
Quoted 1 line
From
d82c0d12c92705ef468683c9b7a8298dd61ed191Mon Sep 17 00:00:00 2001
From: Marcelo Henrique Cerri <[email protected]>
Date: Mon, 13 Mar 2017 12:14:58 -0300
Subject: s390/decompressor: fix initrd corruption caused by bss clear
From: Marcelo Henrique Cerri <[email protected]>
commit d82c0d12c92705ef468683c9b7a8298dd61ed191 upstream.
Reorder the operations in decompress_kernel() to ensure initrd is moved to a safe location before the bss section is zeroed.
During decompression bss can overlap with the initrd and this can corrupt the initrd contents depending on the size of the compressed kernel (which affects where the initrd is placed by the bootloader) and the size of the bss section of the decompressor.
Also use the correct initrd size when checking for overlaps with parmblock.
--- arch/s390/boot/compressed/misc.c | 35 +++++++++++++++++++---------------- 1 file changed, 19 insertions(+), 16 deletions(-)
arch/s390/boot/compressed/misc.c +19 -16
@@ -141,31 +141,34 @@ static void check_ipl_parmblock(void *stunsigned long decompress_kernel (void ) { -unsigned long output_addr; -unsigned char *output; +void *output, *kernel_end; - output_addr = ((unsigned long ) &_end +HEAP_SIZE +4095UL ) &-4096UL ; -check_ipl_parmblock ((void *)0 , output_addr + SZ__bss_start); -memset (&_bss,0 , &_ebss - &_bss); - free_mem_ptr = (unsigned long )&_end; - free_mem_end_ptr = free_mem_ptr +HEAP_SIZE ; - output = (unsigned char *) output_addr; + output = (void *)ALIGN ((unsigned long ) &_end +HEAP_SIZE ,PAGE_SIZE ); + kernel_end = output + SZ__bss_start; +check_ipl_parmblock ((void *)0 , (unsigned long ) kernel_end);#ifdef CONFIG_BLK_DEV_INITRD /* * Move the initrd right behind the end of the decompressed -* kernel image. +* kernel image. This also prevents initrd corruption caused by +* bss clearing since kernel_end will always be located behind the +* current bss section.. */ -if (INITRD_START &&INITRD_SIZE && -INITRD_START < (unsigned long ) output + SZ__bss_start) { -check_ipl_parmblock (output + SZ__bss_start, -INITRD_START +INITRD_SIZE ); -memmove (output + SZ__bss_start, - (void *)INITRD_START ,INITRD_SIZE ); -INITRD_START = (unsigned long ) output + SZ__bss_start; +if (INITRD_START &&INITRD_SIZE && kernel_end > (void *)INITRD_START ) { +check_ipl_parmblock (kernel_end,INITRD_SIZE ); +memmove (kernel_end, (void *)INITRD_START ,INITRD_SIZE ); +INITRD_START = (unsigned long ) kernel_end; }#endif +/* +* Clear bss section. free_mem_ptr and free_mem_end_ptr need to be +* initialized afterwards since they reside in bss. +*/ +memset (&_bss,0 , &_ebss - &_bss); + free_mem_ptr = (unsigned long ) &_end; + free_mem_end_ptr = free_mem_ptr +HEAP_SIZE ; +puts ("Uncompressing Linux... " );__decompress (input_data, input_len,NULL ,NULL , output,0 ,NULL , error);puts ("Ok, booting the kernel.\n" );
Patches currently in stable-queue which might be from [email protected] are
queue-4.10/s390-decompressor-fix-initrd-corruption-caused-by-bss-clear.patch