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authorAta, John (US) <john.ata@baesystems.com>2020-01-28 14:10:21 +0100
committerWaldemar Brodkorb <wbx@openadk.org>2020-01-28 14:15:20 +0100
commitfbe25933d475de36fca739154162e668db2b125f (patch)
tree47d35d3321b33dad3f31231dd74eaaaac893a41f /libc/string/generic/strncmp.c
parent4bae9977da5a322fee4b90c63753420582b84887 (diff)
fix getenv bug
The getenv() library call can trap under certain conditions. It compares the passed in environment variable name (var) with the name=variables (*ep) in the environment area and returns a pointer to the value in the environment if it exists. To accomplish this, it does a memcmp() using the length of the passed in name (len) for each environment variable (*ep) against the passed in name ( var). So memcmp will attempt to scan both strings for len bytes. However, if for some reason, len is equal to or greater than 16 and longer than the length of the *ep in the environment and the *ep resides near the end of a page boundary while the next page is not present or mapped, the memcmp could trap with a sigsegv error while continuing the scan with the optimization read-ahead. However, if strncmp is used instead, there is no problem since both source and destination scanning will stop when either reaches a terminating NULL
Diffstat (limited to 'libc/string/generic/strncmp.c')
0 files changed, 0 insertions, 0 deletions