The code for handing file overwrite incorrectly calculated the amount of data to write when writing to the last non-cluster aligned chunk. Fix this by ensuring that no more data than the 'filesize' is written to disk. While touching min()-based calculations, change it to type-safe min_t() function.
Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com ---
This patch finally fixes the issue revealed by the test script from the previous patch. The correctness of the change has been also verified by the following additional test scripts:
--->8-fat_test2.sh--- #!/bin/bash make sandbox_defconfig make dd if=/dev/zero of=/tmp/10M.img bs=1024 count=10k mkfs.vfat -v /tmp/10M.img cat >/tmp/cmds <<EOF x host bind 0 /tmp/10M.img fatls host 0 mw 0x1000000 0x0a434241 0x1000 # "ABC\n" mw 0x1100000 0x0a464544 0x8000 # "DEF\n" fatwrite host 0 0x1000000 file0001.raw 0x1000 fatwrite host 0 0x1000000 file0002.raw 0x1000 fatwrite host 0 0x1000000 file0003.raw 0x1000 fatwrite host 0 0x1000000 file0004.raw 0x1000 fatwrite host 0 0x1000000 file0005.raw 0x1000 fatrm host 0 file0002.raw fatrm host 0 file0004.raw fatls host 0 fatwrite host 0 0x1100000 file0007.raw 0x2000 fatwrite host 0 0x1100000 file0007.raw 0x1f00 reset EOF ./u-boot </tmp/cmds #verify rm -r /tmp/result /tmp/model mkdir /tmp/result mkdir /tmp/model yes ABC | head -c 4096 >/tmp/model/file0001.raw yes ABC | head -c 4096 >/tmp/model/file0003.raw yes ABC | head -c 4096 >/tmp/model/file0005.raw yes DEF | head -c 7936 >/tmp/model/file0007.raw mcopy -n -i /tmp/10M.img ::file0001.raw /tmp/result mcopy -n -i /tmp/10M.img ::file0003.raw /tmp/result mcopy -n -i /tmp/10M.img ::file0005.raw /tmp/result mcopy -n -i /tmp/10M.img ::file0007.raw /tmp/result hd /tmp/10M.img if diff -urq /tmp/model /tmp/result then echo Test okay else echo Test fail fi --->8-fat_test3.sh--- #!/bin/bash make sandbox_defconfig make dd if=/dev/zero of=/tmp/10M.img bs=1024 count=10k mkfs.vfat -v /tmp/10M.img cat >/tmp/cmds <<EOF x host bind 0 /tmp/10M.img fatls host 0 mw 0x1000000 0x0a434241 0x1000 # "ABC\n" mw 0x1100000 0x0a464544 0x8000 # "DEF\n" fatwrite host 0 0x1000000 file0001.raw 0x1000 fatwrite host 0 0x1000000 file0002.raw 0x1000 fatwrite host 0 0x1000000 file0003.raw 0x1000 fatwrite host 0 0x1000000 file0004.raw 0x1000 fatwrite host 0 0x1000000 file0005.raw 0x1000 fatrm host 0 file0002.raw fatrm host 0 file0004.raw fatls host 0 fatwrite host 0 0x1100000 file0007.raw 0x2000 fatwrite host 0 0x1100000 file0007.raw 0x2100 reset EOF ./u-boot </tmp/cmds #verify rm -r /tmp/result /tmp/model mkdir /tmp/result mkdir /tmp/model yes ABC | head -c 4096 >/tmp/model/file0001.raw yes ABC | head -c 4096 >/tmp/model/file0003.raw yes ABC | head -c 4096 >/tmp/model/file0005.raw yes DEF | head -c 8448 >/tmp/model/file0007.raw mcopy -n -i /tmp/10M.img ::file0001.raw /tmp/result mcopy -n -i /tmp/10M.img ::file0003.raw /tmp/result mcopy -n -i /tmp/10M.img ::file0005.raw /tmp/result mcopy -n -i /tmp/10M.img ::file0007.raw /tmp/result hd /tmp/10M.img if diff -urq /tmp/model /tmp/result then echo Test okay else echo Test fail fi --->8-fat_test4.sh--- #!/bin/bash make sandbox_defconfig make dd if=/dev/zero of=/tmp/10M.img bs=1024 count=10k mkfs.vfat -v /tmp/10M.img cat >/tmp/cmds <<EOF x host bind 0 /tmp/10M.img fatls host 0 mw 0x1000000 0x0a434241 0x1000 # "ABC\n" mw 0x1100000 0x0a464544 0x8000 # "DEF\n" mw 0x1200000 0x0a494847 0x8000 # "GHI\n" fatwrite host 0 0x1000000 file0001.raw 0x1000 fatwrite host 0 0x1000000 file0002.raw 0x1000 fatwrite host 0 0x1000000 file0003.raw 0x1000 fatwrite host 0 0x1000000 file0004.raw 0x1000 fatwrite host 0 0x1000000 file0005.raw 0x1000 fatrm host 0 file0002.raw fatrm host 0 file0004.raw fatls host 0 fatwrite host 0 0x1100000 file0007.raw 0x900 fatwrite host 0 0x1200000 file0007.raw 0x900 0x900 fatwrite host 0 0x1100000 file0007.raw 0x900 0x1200 fatwrite host 0 0x1200000 file0007.raw 0x900 0x1b00 reset EOF ./u-boot </tmp/cmds #verify rm -r /tmp/result /tmp/model mkdir /tmp/result mkdir /tmp/model yes ABC | head -c 4096 >/tmp/model/file0001.raw yes ABC | head -c 4096 >/tmp/model/file0003.raw yes ABC | head -c 4096 >/tmp/model/file0005.raw yes DEF | head -c 2304 >/tmp/model/file0007.raw yes GHI | head -c 2304 >>/tmp/model/file0007.raw yes DEF | head -c 2304 >>/tmp/model/file0007.raw yes GHI | head -c 2304 >>/tmp/model/file0007.raw mcopy -n -i /tmp/10M.img ::file0001.raw /tmp/result mcopy -n -i /tmp/10M.img ::file0003.raw /tmp/result mcopy -n -i /tmp/10M.img ::file0005.raw /tmp/result mcopy -n -i /tmp/10M.img ::file0007.raw /tmp/result hd /tmp/10M.img if diff -urq /tmp/model /tmp/result then echo Test okay else echo Test fail fi --->8--- Feel free to prepare a proper sandbox/py_test based tests based on the provided test scripts. --- fs/fat/fat_write.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c index f946030f7d..8e4a235d7c 100644 --- a/fs/fat/fat_write.c +++ b/fs/fat/fat_write.c @@ -813,7 +813,9 @@ set_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos, __u8 *buffer, offset = 0; else offset = pos - cur_pos; - wsize = min(cur_pos + actsize, filesize) - pos; + wsize = min_t(unsigned long long, actsize, filesize - cur_pos); + wsize -= offset; + if (get_set_cluster(mydata, curclust, offset, buffer, wsize, &actsize)) { printf("Error get-and-setting cluster\n");