Messages in this thread Patch in this message | | | From | Heinrich Schuchardt <> | Subject | [PATCH 3/3] sysctl: detect overflows when converting to int | Date | Sun, 29 Mar 2015 21:28:29 +0200 |
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When converting unsigned long to int overflows may occur. These currently are not detected when writing to the sysctl file system.
E.g. on a system where int has 32 bits and long has 64 bits echo 0x800001234 > /proc/sys/kernel/threads-max has the same effect as echo 0x1234 > /proc/sys/kernel/threads-max
The patch adds the missing check in do_proc_dointvec_conv.
With the patch an overflow will result in an error EINVAL when writing to the the sysctl file system.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> --- kernel/sysctl.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 4d9d139..2fd6b82 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1953,7 +1953,15 @@ static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp, int write, void *data) { if (write) { - *valp = *negp ? -*lvalp : *lvalp; + if (*negp) { + if (*lvalp > (unsigned long) INT_MAX + 1) + return -EINVAL; + *valp = -*lvalp; + } else { + if (*lvalp > (unsigned long) INT_MAX) + return -EINVAL; + *valp = *lvalp; + } } else { int val = *valp; if (val < 0) { -- 2.1.4
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