gh-119511: Fix OOM vulnerability in imaplib #119514
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The IMAP4 client could consume an arbitrary amount of memory when trying to connent to a malicious server, because it read a "literal" data with a single read(size) call, and BufferedReader.read() allocates the bytes object of the specified size before reading. Now the IMAP4 client reads data by chunks, therefore the amount of used memory is limited by the amount of the data actually been sent by the server.
serhiy-storchaka
added
type-security
terryjreedy
reviewed
May 24, 2024
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I've marked this Draft for now as discussion on this on the security response team list is not complete. (we'll summarize that in a public issue once it has settled) |
keepworking
reviewed
May 30, 2024
Lib/imaplib.py
Outdated
| delta = min(cursize, size - cursize) | ||
| data += self.file.read(delta) | ||
| cursize += delta | ||
| return data | ||
| return self.file.read(size) |
There was a problem hiding this comment.
I think you've missed erasing this part.
Lib/imaplib.py
Outdated
| delta = min(cursize, size - cursize) | ||
| data += self.file.read(delta) | ||
| cursize += delta | ||
| return data | ||
| return self.file.read(size) |
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Since this did not block a release, I'm switching it to deferred blocker. |
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The IMAP4 client could consume an arbitrary amount of memory when trying to connent to a malicious server, because it read a "literal" data with a single read(size) call, and BufferedReader.read() allocates the bytes object of the specified size before reading. Now the IMAP4 client reads data by chunks, therefore the amount of used memory is limited by the amount of the data actually been sent by the server.