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Commitb1cd1b6

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brookebasilegregkh
authored andcommitted
USB: gadget: u_f: add overflow checks to VLA macros
size can potentially hold an overflowed value if its assigned expressionis left unchecked, leading to a smaller than needed allocation whenvla_group_size() is used by callers to allocate memory.To fix this, add a test for saturation before declaring variables and anoverflow check to (n) * sizeof(type).If the expression results in overflow, vla_group_size() will return SIZE_MAX.Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>Suggested-by: Kees Cook <keescook@chromium.org>Signed-off-by: Brooke Basile <brookebasile@gmail.com>Acked-by: Felipe Balbi <balbi@kernel.org>Cc: stable <stable@kernel.org>Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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‎drivers/usb/gadget/u_f.h‎

Lines changed: 27 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -14,28 +14,44 @@
1414
#define__U_F_H__
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#include<linux/usb/gadget.h>
17+
#include<linux/overflow.h>
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1819
/* Variable Length Array Macros **********************************************/
1920
#definevla_group(groupname) size_t groupname##__next = 0
2021
#definevla_group_size(groupname) groupname##__next
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#definevla_item(groupname,type,name,n) \
2324
size_t groupname##_##name##__offset = ({ \
24-
size_t align_mask = __alignof__(type) - 1; \
25-
size_t offset = (groupname##__next + align_mask) & ~align_mask;\
26-
size_t size = (n) * sizeof(type); \
27-
groupname##__next = offset + size; \
25+
size_t offset = 0; \
26+
if (groupname##__next != SIZE_MAX) { \
27+
size_t align_mask = __alignof__(type) - 1; \
28+
size_t offset = (groupname##__next + align_mask) \
29+
& ~align_mask; \
30+
size_t size = array_size(n, sizeof(type)); \
31+
if (check_add_overflow(offset, size, \
32+
&groupname##__next)) { \
33+
groupname##__next = SIZE_MAX; \
34+
offset = 0; \
35+
} \
36+
} \
2837
offset; \
2938
})
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#definevla_item_with_sz(groupname,type,name,n) \
32-
size_t groupname##_##name##__sz = (n) * sizeof(type); \
33-
size_t groupname##_##name##__offset = ({ \
34-
size_t align_mask = __alignof__(type) - 1; \
35-
size_t offset = (groupname##__next + align_mask) & ~align_mask;\
36-
size_t size = groupname##_##name##__sz; \
37-
groupname##__next = offset + size; \
38-
offset; \
41+
size_t groupname##_##name##__sz = array_size(n, sizeof(type)); \
42+
size_t groupname##_##name##__offset = ({ \
43+
size_t offset = 0;\
44+
if (groupname##__next != SIZE_MAX) {\
45+
size_t align_mask = __alignof__(type) - 1;\
46+
size_t offset = (groupname##__next + align_mask)\
47+
& ~align_mask;\
48+
if (check_add_overflow(offset, groupname##_##name##__sz,\
49+
&groupname##__next)) {\
50+
groupname##__next = SIZE_MAX;\
51+
offset = 0;\
52+
}\
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}\
54+
offset;\
3955
})
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#definevla_ptr(ptr,groupname,name) \

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