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Juergen Gross
268369d8e3
Today a guest is free to access as many nodes in a single transaction as it wants. This can lead to unbounded memory consumption in Xenstore as there is the need to keep track of all nodes having been accessed during a transaction. In oxenstored the number of requests in a transaction is being limited via a quota maxrequests (default is 1024). As multiple accesses of a node are not problematic in C Xenstore, limit the number of accessed nodes. In order to let read_node() detect a quota error in case too many nodes are being accessed, check the return value of access_node() and return NULL in case an error has been seen. Introduce __must_check and add it to the access_node() prototype. This is part of XSA-326 / CVE-2022-42314. Suggested-by: Julien Grall <julien@xen.org> Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Julien Grall <jgrall@amazon.com>
71 lines
1.9 KiB
C
71 lines
1.9 KiB
C
#ifndef __XEN_TOOLS_LIBS__
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#define __XEN_TOOLS_LIBS__
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#ifndef BUILD_BUG_ON
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#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
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#define BUILD_BUG_ON(p) ({ _Static_assert(!(p), "!(" #p ")"); })
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#else
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#define BUILD_BUG_ON(p) ((void)sizeof(char[1 - 2 * !!(p)]))
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#endif
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#endif
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#ifndef ARRAY_SIZE
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#define ARRAY_SIZE(a) (sizeof(a) / sizeof(*a))
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#endif
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#ifndef MAX
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#define MAX(x, y) ((x) > (y) ? (x) : (y))
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#endif
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#ifndef MIN
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#define MIN(x, y) ((x) < (y) ? (x) : (y))
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#endif
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#ifndef min
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#define min(x, y) \
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({ \
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const typeof(x) _x = (x); \
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const typeof(y) _y = (y); \
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(void) (&_x == &_y); \
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(_x < _y) ? _x : _y; \
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})
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#endif
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#ifndef max
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#define max(x, y) \
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({ \
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const typeof(x) _x = (x); \
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const typeof(y) _y = (y); \
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(void)(&_x == &_y); \
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(_x > _y) ? _x : _y; \
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})
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#endif
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#ifndef min_t
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#define min_t(type, x, y) \
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({ \
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const type _x = (x); \
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const type _y = (y); \
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(_x < _y) ? _x: _y; \
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})
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#endif
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#ifndef max_t
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#define max_t(type, x, y) \
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({ \
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const type _x = (x); \
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const type _y = (y); \
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(_x > _y) ? _x: _y; \
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})
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#endif
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#ifndef ROUNDUP
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#define ROUNDUP(_x,_w) (((unsigned long)(_x)+(1UL<<(_w))-1) & ~((1UL<<(_w))-1))
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#endif
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#ifndef __must_check
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#define __must_check __attribute__((__warn_unused_result__))
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#endif
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#endif /* __XEN_TOOLS_LIBS__ */
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