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| author | Siddhesh Poyarekar <siddhesh@redhat.com> | 2014-01-27 16:49:33 +0530 |
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| committer | Siddhesh Poyarekar <siddhesh@redhat.com> | 2014-01-27 16:49:33 +0530 |
| commit | d7b00f98106a0f1e3d753b135eeb97dfdf6e2e74 (patch) | |
| tree | 4b8860ccb6e18818323f06063edba56aa4f2d3d3 | |
| parent | af37a8a3496327a6e5617a2c76f17aa1e8db835e (diff) | |
| download | glibc-d7b00f98106a0f1e3d753b135eeb97dfdf6e2e74.tar.gz glibc-d7b00f98106a0f1e3d753b135eeb97dfdf6e2e74.tar.xz glibc-d7b00f98106a0f1e3d753b135eeb97dfdf6e2e74.zip | |
Fix invalid memory access when parsing netgroup files with blank lines (BZ #16506)
The netgroups file parsing code tries to access the character before the newline in parsed lines to see if it is a backslash (\). This results in an access before the block allocated for the line if the line is blank, i.e. does not have anything other than the newline character. This doesn't seem like it will cause any crashes because the byte belongs to the malloc metadata block and hence access to it will always succeed. There could be an invalid alteration in code flow where a blank line is seen as a continuation due to the preceding byte *happening* to be '\\'. This could be done by interposing malloc, but that's not really a security problem since one could interpose getnetgrent_r itself and achieve a similar 'exploit'. The possibility of actually exploiting this is remote to impossible since it also requires the previous line to end with a '\\', which would happen only on invalid configurations.
| -rw-r--r-- | ChangeLog | 4 | ||||
| -rw-r--r-- | nss/nss_files/files-netgrp.c | 3 |
2 files changed, 6 insertions, 1 deletions
diff --git a/ChangeLog b/ChangeLog index a1f549e655..322ec08cc5 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,9 @@ 2014-01-27 Siddhesh Poyarekar <siddhesh@redhat.com> + [BZ #16506] + * nss/nss_files/files-netgrp.c (_nss_files_setnetgrent): Avoid + access beyond array bounds when parsing netgroups file. + * nscd/netgroupcache.c (addgetnetgrentX): Compute offset from the old buffer before realloc. diff --git a/nss/nss_files/files-netgrp.c b/nss/nss_files/files-netgrp.c index 339f704c93..34eae4c5be 100644 --- a/nss/nss_files/files-netgrp.c +++ b/nss/nss_files/files-netgrp.c @@ -103,7 +103,8 @@ _nss_files_setnetgrent (const char *group, struct __netgrent *result) result->cursor += (curlen - group_len) - 1; } - while (line[curlen - 1] == '\n' && line[curlen - 2] == '\\') + while (curlen > 1 && line[curlen - 1] == '\n' + && line[curlen - 2] == '\\') { /* Yes, we have a continuation line. */ if (found) |