misc-utils: docfdisk.c: fix potential integer underflow in partition size calculation

report of the static analyzer:
Possible integer underflow: right operand is tainted.
An integer underflow may occur due to arithmetic
operation (unsigned subtraction) between
variables 'totblocks' and 'block', where 'totblocks'
is in range { [0, 4294967295] }, and 'block' is tainted { [0, 4294967295] }

correct explained:
Added validation check before calculating remaining
space for partition. The issue occurred when setting
the last partition size to 0, which triggers calculation
'totblocks - block'. Without validation, if block >= totblocks,
this would result in integer underflow due to unsigned
arithmetic, potentially creating a partition with enormous
size and leading to device corruption.

Signed-off-by: Anton Moryakov <ant.v.moryakov@gmail.com>
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

0 files changed, 0 insertions, 0 deletions