tree d0e6d00e73f2f91176051ddee7a1ef92a6577719
parent 786918a584155a0ff600fc59a72688e5cabfe5d9
author Darrick J. Wong <djwong@kernel.org> 1643068111 -0800
committer Darrick J. Wong <djwong@kernel.org> 1643301253 -0800

xfs: reject crazy array sizes being fed to XFS_IOC_GETBMAP*

Syzbot tripped over the following complaint from the kernel:

WARNING: CPU: 2 PID: 15402 at mm/util.c:597 kvmalloc_node+0x11e/0x125 mm/util.c:597

While trying to run XFS_IOC_GETBMAP against the following structure:

struct getbmap fubar = {
	.bmv_count	= 0x22dae649,
};

Obviously, this is a crazy huge value since the next thing that the
ioctl would do is allocate 37GB of memory.  This is enough to make
kvmalloc mad, but isn't large enough to trip the validation functions.
In other words, I'm fussing with checks that were **already sufficient**
because that's easier than dealing with 644 internal bug reports.  Yes,
that's right, six hundred and forty-four.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>