From 8961c8ad252b8af887439e4e5c6c1bc0c912f2de Mon Sep 17 00:00:00 2001 From: Mark Tomlinson Date: Wed, 29 Aug 2018 10:51:14 +1200 Subject: [PATCH] tools: mkimage: Ensure munmap unmaps the same length that was mapped The set_header call in kwbimage.c adds a checksum to the end of the image in addition to setting up the header. It 'helpfully' updates the st_size to match the fact that the file is now longer. However, mkimage uses this length in the munmap call. This can lead to unmapping an extra page, of perhaps required data. When this happens, a SEGV can occur. To prevent this from happening, the munmap call now uses the same length that was passed to mmap. This could also have been fixed by not changing the length in kwbimage.c, however changing it in the main file means that other plugins will also not fall for the same trap. Signed-off-by: Mark Tomlinson Signed-off-by: Chris Packham [cp: resolve checkpatch complaints] Tested-by: Chris Packham --- tools/mkimage.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/tools/mkimage.c b/tools/mkimage.c index e0d4d20..6abd4d6 100644 --- a/tools/mkimage.c +++ b/tools/mkimage.c @@ -318,6 +318,7 @@ int main(int argc, char **argv) struct image_type_params *tparams = NULL; int pad_len = 0; int dfd; + size_t map_len; params.cmdname = *argv; params.addr = 0; @@ -576,7 +577,8 @@ int main(int argc, char **argv) } params.file_size = sbuf.st_size; - ptr = mmap(0, sbuf.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, ifd, 0); + map_len = sbuf.st_size; + ptr = mmap(0, map_len, PROT_READ | PROT_WRITE, MAP_SHARED, ifd, 0); if (ptr == MAP_FAILED) { fprintf (stderr, "%s: Can't map %s: %s\n", params.cmdname, params.imagefile, strerror(errno)); @@ -600,7 +602,7 @@ int main(int argc, char **argv) params.cmdname, tparams->name); } - (void) munmap((void *)ptr, sbuf.st_size); + (void)munmap((void *)ptr, map_len); /* We're a bit of paranoid */ #if defined(_POSIX_SYNCHRONIZED_IO) && \