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Fail explicitly on length overflow.

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Instead of aborting when FileMap::create detects an overflow, detect the
overflow directly and fail the call.

Bug: 156997193

Test: Ran unit tests, including new unit test that aborted before.
Change-Id: Ie49975b8949fd12bbde14346ec9bbb774ef88a51
Merged-In: Ie49975b8949fd12bbde14346ec9bbb774ef88a51
(cherry picked from commit 68604b9c29)
This commit is contained in:
Christopher Ferris 2020-05-26 10:33:18 -07:00
parent 75b3266e22
commit f846413e62
2 changed files with 18 additions and 1 deletions
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6
libutils/FileMap.cpp
View file

@ -189,7 +189,11 @@ bool FileMap::create(const char* origFileName, int fd, off64_t offset, size_t le
int adjust = offset % mPageSize;
off64_t adjOffset = offset - adjust;
size_t adjLength = length + adjust;
size_t adjLength;
if (__builtin_add_overflow(length, adjust, &adjLength)) {
ALOGE("adjusted length overflow: length %zu adjust %d", length, adjust);
return false;
}
int flags = MAP_SHARED;
int prot = PROT_READ;

13
libutils/FileMap_test.cpp
View file

@ -32,3 +32,16 @@ TEST(FileMap, zero_length_mapping) {
ASSERT_EQ(0u, m.getDataLength());
ASSERT_EQ(4096, m.getDataOffset());
}
TEST(FileMap, offset_overflow) {
// Make sure that an end that overflows SIZE_MAX will not abort.
// See http://b/156997193.
TemporaryFile tf;
ASSERT_TRUE(tf.fd != -1);
off64_t offset = 200;
size_t length = SIZE_MAX;
android::FileMap m;
ASSERT_FALSE(m.create("test", tf.fd, offset, length, true));
}