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devstat_selectdevs: resize dev_select only after copying data out of it

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The resizing could be a downsizing so some data would be lost and we
could attempt to read past the end of the new memory allocation.

MFC after:	2 weeks
Sponsored by:	Panzura
This commit is contained in:
Andriy Gapon 2019-12-03 09:48:43 +00:00
parent 3995097fde
commit 84a03ac69a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=355325
1 changed files with 7 additions and 2 deletions
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9
lib/libdevstat/devstat.c
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@ -584,10 +584,10 @@ devstat_selectdevs(struct device_selection **dev_select, int *num_selected,
* In this case, we have selected devices before, but the device
* list has changed since we last selected devices, so we need to
* either enlarge or reduce the size of the device selection list.
* But delay the resizing until after copying the data to old_dev_select
* as to not lose any data in the case of reducing the size.
*/
} else if (*num_selections != numdevs) {
*dev_select = (struct device_selection *)reallocf(*dev_select,
numdevs * sizeof(struct device_selection));
*select_generation = current_generation;
init_selections = 1;
/*
@ -645,6 +645,11 @@ devstat_selectdevs(struct device_selection **dev_select, int *num_selected,
sizeof(struct device_selection) * *num_selections);
}
if (!changed && *num_selections != numdevs) {
*dev_select = (struct device_selection *)reallocf(*dev_select,
numdevs * sizeof(struct device_selection));
}
if (init_selections != 0) {
bzero(*dev_select, sizeof(struct device_selection) * numdevs);