flb_utils: fix out of bounds write on invalid utf-8 #875
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In flb_utils_write_str, written and *off could be set
to an incorrect large value on invalid UTF-8 input.
Later, this would lead to an out of bounds write when
nul-terminating the string:
Invalid write of size 1
at 0x44378B: flb_msgpack_to_json (in /build/bin/fluent-bit)
by 0x443B78: flb_msgpack_raw_to_json_str (in /build/bin/fluent-bit)
by 0x47576D: kafka_rest_format (in /build/bin/fluent-bit)
by 0x4758E9: cb_kafka_flush (in /build/bin/fluent-bit)
by 0x434A71: output_pre_cb_flush (in /build/bin/fluent-bit)
by 0x50DF26: co_init (in /build/bin/fluent-bit)
Address 0x4d9985e is on thread 1's stack
Input file (base64 encoded):
MAowCjAwCjAwADAKMDAwMDAK/wowCjAwCoAK
Signed-off-by: Carl Henrik Lunde <[email protected]>
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@edsiper please double check this, but I cannot see why written is set initially, and if the loop terminates before setting written again at least once we run into this issue. This also means buffers are often seen as to small even if they were large enough. |
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taking a look now... |
edsiper
approved these changes
Nov 2, 2018
|
thanks for troubleshoot and fix this |
edsiper
pushed a commit
that referenced
this pull request
Nov 2, 2018
In flb_utils_write_str, written and *off could be set
to an incorrect large value on invalid UTF-8 input.
Later, this would lead to an out of bounds write when
nul-terminating the string:
Invalid write of size 1
at 0x44378B: flb_msgpack_to_json (in /build/bin/fluent-bit)
by 0x443B78: flb_msgpack_raw_to_json_str (in /build/bin/fluent-bit)
by 0x47576D: kafka_rest_format (in /build/bin/fluent-bit)
by 0x4758E9: cb_kafka_flush (in /build/bin/fluent-bit)
by 0x434A71: output_pre_cb_flush (in /build/bin/fluent-bit)
by 0x50DF26: co_init (in /build/bin/fluent-bit)
Address 0x4d9985e is on thread 1's stack
Input file (base64 encoded):
MAowCjAwCjAwADAKMDAwMDAK/wowCjAwCoAK
Signed-off-by: Carl Henrik Lunde <[email protected]>
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In flb_utils_write_str, written and *off could be set
to an incorrect large value on invalid UTF-8 input.
Later, this would lead to an out of bounds write when
nul-terminating the string:
Input file (base64 encoded):