From cc2f60c13f6aaf1bd277cf10c8b375c2e4a695b7 Mon Sep 17 00:00:00 2001 From: Joshua Watt Date: Wed, 28 Aug 2024 08:37:57 -0600 Subject: [PATCH] android_ab: Fixes: Fix backup offset calculation The backup offset is in bytes, but was incorrectly be interpreted as blocks, leading to it being written to the wrong location. Fix the calculation, clarify that ANDROID_AB_BACKUP_OFFSET is in bytes and must be a multiple of the block size, and add a runtime check to validate the offset. Signed-off-by: Joshua Watt Reviewed-by: Mattijs Korpershoek Fixes: 3430f24bc69d ("android_ab: Try backup booloader_message") Link: https://lore.kernel.org/r/20240828143924.3987331-1-JPEWhacker@gmail.com Signed-off-by: Mattijs Korpershoek --- boot/android_ab.c | 9 +++++++-- common/Kconfig | 3 ++- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/boot/android_ab.c b/boot/android_ab.c index 143f373aae..1196a189ed 100644 --- a/boot/android_ab.c +++ b/boot/android_ab.c @@ -139,8 +139,13 @@ static int ab_control_store(struct blk_desc *dev_desc, { ulong abc_offset, abc_blocks, ret; - abc_offset = offset + - offsetof(struct bootloader_message_ab, slot_suffix) / + if (offset % part_info->blksz) { + log_err("ANDROID: offset not block aligned\n"); + return -EINVAL; + } + + abc_offset = (offset + + offsetof(struct bootloader_message_ab, slot_suffix)) / part_info->blksz; abc_blocks = DIV_ROUND_UP(sizeof(struct bootloader_control), part_info->blksz); diff --git a/common/Kconfig b/common/Kconfig index 83c81edac2..e1b8557e0c 100644 --- a/common/Kconfig +++ b/common/Kconfig @@ -986,7 +986,8 @@ config ANDROID_AB_BACKUP_OFFSET help If non-zero, a backup bootloader message starting at this offset in the partition will tried in the event that the primary one (starting - at offset 0) fails its checksum. + at offset 0) fails its checksum. The offset is in bytes and must be + multiple of the block size. endmenu -- 2.39.5