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Fix overflow 

`totalsize` might be a big (invalid) number so instead of checking the end address we check the size of the image.

Fix #4049
This commit is contained in:
Shaka Huang 2021-03-24 18:02:46 +08:00 committed by GitHub
parent 336f1687c1
commit e3801d6965
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1 changed files with 2 additions and 2 deletions
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4
native/jni/magiskboot/bootimg.cpp
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@ -205,12 +205,12 @@ static int find_dtb_offset(uint8_t *buf, unsigned sz) {
// Check that fdt_header.totalsize does not overflow kernel image size
uint32_t totalsize = fdt32_to_cpu(fdt_hdr->totalsize);
if (curr + totalsize > end)
if (totalsize > end - curr)
continue;
// Check that fdt_header.off_dt_struct does not overflow kernel image size
uint32_t off_dt_struct = fdt32_to_cpu(fdt_hdr->off_dt_struct);
if (curr + off_dt_struct > end)
if (off_dt_struct > end - curr)
continue;
// Check that fdt_node_header.tag of first node is FDT_BEGIN_NODE