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authorLinus Torvalds <torvalds@g5.osdl.org>2006-04-18 13:02:48 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-04-18 13:02:48 -0700
commit0a489cb3b6a7b277030cdbc97c2c65905db94536 (patch)
tree1a746dc22ed12badc30198c8eb5065535a76bbb0 /Kbuild
parentac69e973ff0660e455f4ba1ddd4dcce4ae70ed1a (diff)
downloadlinux-0a489cb3b6a7b277030cdbc97c2c65905db94536.tar.bz2
x86: don't allow tail-calls in sys_ftruncate[64]()
Gcc thinks it owns the incoming argument stack, but that's not true for "asmlinkage" functions, and it corrupts the caller-set-up argument stack when it pushes the third argument onto the stack. Which can result in %ebx getting corrupted in user space. Now, normally nobody sane would ever notice, since libc will save and restore %ebx anyway over the system call, but it's still wrong. I'd much rather have "asmlinkage" tell gcc directly that it doesn't own the stack, but no such attribute exists, so we're stuck with our hacky manual "prevent_tail_call()" macro once more (we've had the same issue before with sys_waitpid() and sys_wait4()). Thanks to Hans-Werner Hilse <hilse@sub.uni-goettingen.de> for reporting the issue and testing the fix. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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